COG Thread Dimensions Explained: 2-1, 3-1, 4D, 6D and Bidirectional Cogs
The number in a cog thread's name describes how many directions its barbs lock into tissue, not how strong it is. A standard barbed cog grips in one or two planes; a 3D cog anchors in three; 4D in four; 6D in six. More directions mean more fixation points against the vector of pull — which matters most where skin is thin or mobile. The trade-off is that higher-dimensional cogs are thicker (USP-1 to USP-2) and need larger needles or cannulas, so they are not automatically the right choice for every area.
On this page:
- What "dimension" actually refers to
- Why spiral placement changes anchoring behaviour
- Comparing the AuroThread cog range
- Choosing between them
- Where these threads are indicated
- Sourcing considerations for clinics and distributors
- Frequently asked questions
- AuroThread Product Range
What "dimension" actually refers to
A cog thread is a PDO, PCL or PLLA suture cut with angled barbs along its length. When the thread is placed and pulled, the barbs open against the surrounding tissue and hold. The geometry of those barbs determines where the holding force is directed:
| Thread | Barb geometry | Locking directions | Construction |
|---|---|---|---|
| COG2-1 | Barbed, moulded | 1 plane | Single-direction barbs |
| COG3-1 | Double-sided, single direction | 2 planes, one direction | Barbs both sides, same facing |
| COG4-1 | Double-sided, bidirectional | 2 planes, two directions | Barbs both sides, opposing facing |
| COG5-1 | Single-sided, bidirectional | 1 plane, two directions | One side, opposing facing |
| COG 3D | 360° spiral barbs | 3 directions | Spirally placed around the suture |
| COG 4D | 360° spiral barbs | 4 directions | Spirally placed around the suture |
| Bidirectional COG 4D | 360° spiral, bidirectional | 4 directions | Spiral barbs with opposing anchors |
| COG 6D | 360° spiral barbs | 6 directions | Spirally placed around the suture |
The key structural difference between the numbered COG-2-1/3-1/4-1/5-1 series and the 3D/4D/6D series is placement pattern. The first series arranges barbs on flat sides of the suture. The 3D/4D/6D series places them on a 360° spiral, so each barb is offset from the last around the circumference of the thread rather than sitting in the same plane.
For the design-by-design breakdown of the barbed family, see PDO Cog Threads: How They Lift.
Why spiral placement changes anchoring behaviour
A flat-arranged barb set resists pull in the plane it was cut for. Rotate the thread even slightly during placement and holding force drops, because the barbs are no longer presented square-on to the tissue they must engage.
Spiral placement distributes barbs around the circumference, so the thread engages tissue in several directions regardless of how it settles. In practice that gives two things:
- Smoother anchoring. Rather than a small number of barbs taking the whole load, force is spread over more points around the thread. This is the "effective and smooth anchoring" described in the AuroThread catalogue.
- Higher resistance to migration in areas with repeated movement — the jawline, the neck, around the mouth.
A moulded cog produced without heat is a separate construction; that is covered in the Molding Thread Guide.
Comparing the AuroThread cog range
All specifications below are taken from the AuroThread PDO catalogue. Format is needle length → suture length.
COG-1 series (flat-arranged barbs)
| Model | Barb structure | Needle type | Needle size | Needle → suture length | Suture thickness |
|---|---|---|---|---|---|
| COG2-1 | Nose thread profile | L Cannula | 19G | 38 mm → 50 mm · 60 mm → 80 mm | USP-2 |
| COG3-1 | Double sided, single direction | Sharp Needle | 21G | 60 mm → 120 mm · 90 mm → 150 mm | USP-2 |
| COG4-1 | Double sided, bidirectional | Sharp Needle | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP-2 |
| COG4-1 | Double sided, bidirectional | L Cannula | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP-2 |
| COG4-1 | Double sided, bidirectional | W Cannula | 19G | 100 mm → 160 mm | USP-2 |
| COG5-1 | Single sided, bidirectional | Sharp Needle | 21G | 60 mm → 120 mm · 90 mm → 150 mm | USP-2 |
3D / 4D / 6D series (360° spiral barbs)
| Model | Locking directions | Needle type | Needle size | Needle → suture length | Suture thickness |
|---|---|---|---|---|---|
| COG 3D | 3 | Sharp Needle | 23G | 60 mm → 120 mm · 90 mm → 160 mm | USP2 |
| COG 3D | 3 | Sharp Needle | 19G | 100 mm → 160 mm | USP2 |
| COG 3D | 3 | L Cannula | 19G / 21G | 100 mm → 160 mm · 100 mm → 120 mm · 60 mm → 160 mm | USP2 |
| COG 4D | 4 | Sharp Needle | 23G | 60 mm → 120 mm · 90 mm → 150 mm | USP2 |
| COG 4D | 4 | Sharp Needle | 19G | 100 mm → 160 mm | USP2 |
| COG 4D | 4 | L Cannula | 19G / 21G | 100 mm → 160 mm · 60 mm → 120 mm | USP2 |
| COG 4D | 4 | W Cannula | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP2 |
| Bidirectional COG 4D | 4 (bidirectional) | Sharp Needle | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP2 |
| Bidirectional COG 4D | 4 (bidirectional) | L Cannula | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP2 |
| Bidirectional COG 4D | 4 (bidirectional) | W Cannula | 19G / 21G | 100 mm → 160 mm · 90 mm → 150 mm | USP2 |
| COG 6D | 6 | L Cannula | 19G | 100 mm → 160 mm | USP-1 |
| COG 6D | 6 | W Cannula | 19G | 100 mm → 160 mm | USP-1 |
Every model above is supplied in PDO, PCL and PLLA; the full catalogue sits in the PDO thread collection.
Choosing between them
Three practical rules govern selection.
1. Match the dimension to how mobile the area is. Thin, mobile tissue with repeated muscular movement — the neck, jawline, perioral area — benefits from more locking directions. Flatter, less mobile planes are adequately served by the lower-dimensional models.
2. Match the needle to the plane you can safely reach. COG 6D is supplied only on a 19G L or W cannula. That is a blunt-tip device, which is why it is used where a sharp needle would be a hazard — around vessels, in the temple, in the periorbital region. If your intended plane needs a 23G sharp entry, COG 3D and 4D are the options.
3. Thicker does not mean better. COG 6D is USP-1, the heaviest gauge in the range. It holds strongly but is also the least discreet and requires the largest entry. For superficial work, a USP-2 or finer thread on a 23G or 25G needle will give a better tissue result even though its dimension number is lower.
For the broader mono / screw / cog taxonomy, see PDO Thread Types and Application Areas.
Where these threads are indicated
The AuroThread catalogue lists the following application areas for the spiral cog range: forehead wrinkles, frown lines, crow's feet, wrinkled nose, lip wrinkles, neck lifting and neck wrinkles, lacrimal sulcus, nasolabial folds, cheek lifting, plus chest, leg and hip for body indications.
Indication is a clinical decision based on tissue quality, laxity and vascular anatomy at the site. The list above describes where the product is designed to be used — not a treatment protocol.
The blunt-cannula constructions used around the eye are detailed in the nose and eye thread guide.
Sourcing considerations for clinics and distributors
When specifying cog threads for a clinic or a distribution list, three details are worth confirming with any supplier, because they determine whether two "19G COG 4D" products are actually interchangeable:
- Barb pattern documentation. Ask which of the numbered structures (single-sided, double-sided single direction, double-sided bidirectional, single-sided bidirectional) the model uses. "Cog 4D" alone does not specify this.
- Suture thickness in USP. Two threads can share a needle size and thread length but differ in USP grade, which changes both holding force and how visible the thread is under thin skin.
- Sterilisation and single-use marking. AuroThread PDO and PCL sutures are sterilised by E.O. gas, marked single use only, and to be stored below 30 °C. Confirm these appear on the label, not only in the specification sheet.
AuroThread supplies the full cog range — flat-arranged and 360° spiral, in PDO, PCL and PLLA — under private label and OEM arrangements. Catalogue specifications and sample requests are available through Contact Us.
Private-label and OEM terms are set out in our OEM and private label guide.
Frequently asked questions
Is a 6D cog thread stronger than a 4D cog thread?
It has more locking directions — six versus four — which means more fixation points against the vector of pull. That is not the same as being stronger in every situation. COG 6D is USP-1, the heaviest gauge in the AuroThread range, and is supplied only on a 19G cannula. Where the plane calls for a finer thread or a sharper entry point, a 4D on a 21G or 23G needle can produce a better result.
What does the number in COG2-1, COG3-1, COG4-1 or COG5-1 mean?
These are barb-pattern designations, not dimension counts. COG2-1 uses a nose-thread barb profile; COG3-1 is double sided with barbs facing one direction; COG4-1 is double sided with bidirectional barbs; COG5-1 is single sided with bidirectional barbs. The 3D/4D/6D naming is separate and refers to 360° spiral barb placement.
Can cog threads be used on the body, not just the face?
The AuroThread catalogue lists chest, leg and hip among the application areas for the spiral cog range, and arm and body contouring for Cones Cog. Body indications differ from facial ones in tissue thickness and required thread length — for example the Double Needle + COG4D is supplied with a 400 mm suture length for larger vectors.
Do all AuroThread cog threads come in PDO, PCL and PLLA?
The catalogue specification tables for the cog range are headed "PDO PCL PLLA THREAD", covering all three absorbable materials. Absorption differs by material: PDO absorbs in 3–6 months, PCL lasts more than two years, and PLLA two years or more. Confirm the material for your specific model and intended duration when ordering.
What should a clinic check before ordering in bulk?
Confirm the barb pattern, the suture thickness in USP grade, the needle type and size against the plane you intend to treat, and the label markings — E.O. gas sterilisation, single use only, storage below 30 °C. AuroThread offers catalogue documentation, samples and private-label supply for clinics and distributors.
AuroThread Product Range
AuroThread manufactures lifting threads in all three absorbable materials, factory-direct, with OEM and private-label options for clinics and distributors.
- PDO Mono & Cog Thread Range — Complete mono, screw, tornado and cog designs in PDO, PCL and PLLA
- PLLA Lifting Threads — Longest effect window of the three absorbable materials
- PCL Lifting Threads — Sustained collagen stimulation with high elasticity
- Full PDO / PLLA / PCL Range — All three materials across every design family
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Educational and product-information content only — not medical advice. Absorbable threads are medical devices; product selection, placement technique and indications are the responsibility of a licensed practitioner. © 2026 Auro Technology Limited.