Regular price SFr. 825.00
Unit price per
Double K Delfit Carbon Bi-Fins
The Double K Delfit Carbon Bi-Fins are high-performance carbon freediving fins built for divers who want efficient propulsion, precise blade response and a secure foot pocket connection.
The Delfit system combines high-elastic carbon blades, autoclave-molded construction and Double K’s dedicated Delfit foot pockets. The result is a responsive carbon fin setup for dynamic apnea, CWT, depth training and serious freediving technique work.
Available in White, Red and Black, with blade stiffness options S, MS and M.
Why choose the Double K Delfit Carbon Bi-Fins?
Good carbon bifins are not only about blade material. The connection between foot pocket, rails and blade decides how much of your kick actually becomes propulsion. The Delfit Carbon Bi-Fins are designed around that connection: a secure Delfit foot pocket, a high-elastic carbon blade and a directional wing concept that helps convert a clean kick into forward movement.
Double K positions the Delfit system around three core ideas: lightweight construction, positive buoyancy and comfort. The foot pocket is designed to sit closely around the foot, especially when used with silicone socks, improving force transfer while reducing empty space inside the pocket.
Main benefits
- High-elastic carbon blades for strong and responsive propulsion
- Autoclave-molded carbon construction for consistent blade performance
- Delfit foot pocket system for secure fit and efficient force transfer
- Energy compression and directional wing concept for cleaner kick efficiency
- Positive-buoyancy design focus for balanced handling in the water
- Three stiffness options: S, MS and M
- Three colour setups: White, Red and Black
- Suitable for dynamic apnea, CWT, depth training and regular freediving sessions
Delfit foot pocket system
The Delfit foot pocket is one of the strongest parts of this fin system. In a carbon bifin, the foot pocket is not just a comfort component. It controls how directly the force from your foot reaches the blade.
If the foot pocket is too loose, power is lost before the blade reacts. If it is too tight, comfort and relaxation suffer. The Delfit system is designed to create a close, stable fit while keeping enough comfort for repeated pool sets, depth sessions and longer open-water training.
Double K specifically refers to the use of silicone soft socks. According to the manufacturer’s sizing graphic, wearing Double K Silicone Soft Socks makes the fit approximately 1 mm tighter, helping remove empty space, improve power transfer and reduce foot discomfort.
Blade and propulsion concept
The Delfit carbon blade uses a high-elastic carbon construction and a directional wing concept to support rebound, stability and forward drive. The aim is not simply to make the blade stiff. The aim is to create controlled elastic response from a clean, efficient kick.
Double K describes the Delfit concept around stronger propulsion, improved straight-line stability, increased speed and reduced physical effort during finning. This should be understood as the design intention: efficient movement, better direction and less wasted energy.
Blade stiffness guide
| Stiffness | Best use | Kaluna recommendation |
|---|---|---|
| S | Dynamic apnea / pool training | Choose S if you want a softer blade, easier rhythm and repeated pool sets. |
| MS | Allround freediving | Choose MS if you want the safest default option for most freedivers. |
| M | Depth / stronger kick | Choose M if you are a stronger diver or prefer more resistance and stronger blade response. |
If you are unsure, MS is usually the most sensible allround choice. S is more dynamic-focused. M is more depth- and power-focused.
Colour options
The Double K Delfit Carbon Bi-Fins are available in three colour setups:
- White - clean, bright and highly visible in pool photos and videos
- Red - strong contrast and the most aggressive visual setup
- Black - minimal, technical and understated
The blade remains carbon-dark. The selected colour mainly affects the foot pockets, rails and logo/trim details.
Foot pocket size guide
For the best fit, choose the Delfit foot pocket size based on measured foot length in millimetres, forefoot width and whether you use silicone socks. EU shoe sizes are included as a practical reference, but foot length is more reliable than shoe size alone.
Double K Silicone Soft Socks make the fit approximately 1 mm tighter. This can help remove empty space, improve power transfer and reduce foot discomfort.
Important: Double K’s size chart includes #1 for very small standard forefeet, but the public Delfit Carbon Bi-Fins product selector currently lists foot pocket sizes #2–#8. If your table result is #1, contact us before ordering.
For high-end carbon fins, sizing should not be guessed. Send us your measured foot length, forefoot width and sock choice if you are unsure.
Text version of the Delfit foot pocket size guide
Barefoot / without silicone socks
| Foot length / EU approx. | Wide forefoot | Standard forefoot | Narrow forefoot |
|---|---|---|---|
| 210 mm / EU 32–33 | #2 | #1 | - |
| 220 mm / EU 34–35 | #3 | #2 | - |
| 230 mm / EU 36–37 | #4 | #3 | #2 |
| 240 mm / EU 37–38 | #5 | #4 | #3 |
| 250 mm / EU 38–39 | #6 | #5 | #4 |
| 260 mm / EU 40–41 | #7 | #6 | #5 |
| 270 mm / EU 42–43 | #8 | #7 | #6 |
| 280 mm / EU 44–45 | - | #8 | #7 |
With Double K Silicone Soft Socks
| Foot length / EU approx. | Wide forefoot | Standard forefoot | Narrow forefoot |
|---|---|---|---|
| 210 mm / EU 32–33 | #3 | #2 | - |
| 220 mm / EU 34–35 | #4 | #3 | #2 |
| 230 mm / EU 36–37 | #5 | #4 | #3 |
| 240 mm / EU 37–38 | #6 | #5 | #4 |
| 250 mm / EU 38–39 | #7 | #6 | #5 |
| 260 mm / EU 40–41 | #8 | #7 | #6 |
| 270 mm / EU 42–43 | - | #8 | #7 |
| 280 mm / EU 44–45 | - | - | #8 |
Technical details
| Brand | Double K |
|---|---|
| Model | Delfit Carbon Bi-Fins |
| Product type | Carbon freediving bifins |
| Blade material | High-elastic carbon |
| Carbon weave | 3K Twill |
| Carbon layers | 15 layers |
| Manufacturing method | Autoclave molding |
| Foot pocket material | Rubber + EVA |
| Blade stiffness | S, MS, M |
| Colours | White, Red, Black |
| Foot pocket sizes | #2, #3, #4, #5, #6, #7, #8 |
| Approx. dimensions | 68 cm length x 19 cm width per fin |
| Manufacturer weight note | 900 g per blade, size #2, according to the manufacturer graphic |
| Recommended use | Dynamic apnea, CWT, depth training, pool training, open-water freediving |
Are these the right fins for you?
Choose the Double K Delfit Carbon Bi-Fins if you want a serious carbon bifin setup for structured freediving training. They are best suited to divers who want strong propulsion, clean blade response and a close foot pocket connection.
They make sense for:
- Dynamic apnea training
- CWT and depth-focused freediving
- Pool technique development
- Open-water freediving sessions
- Freedivers moving from basic fins into performance carbon gear
- Athletes who want to choose blade stiffness instead of buying a generic setup
- Divers who care about foot pocket fit and power transfer
Kaluna Freediving Opinion
The Delfit Carbon Bi-Fins are interesting because Double K does not treat the foot pocket as an afterthought. For carbon bifins, that matters. A blade can be excellent, but if the foot pocket connection is weak, power transfer becomes sloppy.
The strongest setup for most freedivers will usually be MS stiffness, unless the use case is clearly dynamic-specific or depth-specific. S makes sense for pool rhythm and repeated dynamic work. M makes sense for stronger divers who want more resistance and depth performance.
Colour is personal. The important decisions are foot pocket size, socks and blade stiffness. If those are right, the fins can work as a long-term performance tool. If those are wrong, even a good carbon blade will feel wrong in the water.
FAQ
Which stiffness should I choose?
Choose S for dynamic apnea and softer pool work, MS for the most versatile allround setup, and M for stronger divers or depth-focused training. If you are unsure, MS is usually the safest starting point.
Which colour should I choose?
Choose White for a clean and visible look, Red for the strongest visual contrast, or Black for a more minimal technical setup. Colour is personal; stiffness and foot pocket size matter more.
How should the foot pocket fit?
The fit should be close and stable without creating painful pressure points. If the foot moves inside the pocket before the blade reacts, power transfer becomes less efficient.
Should I use silicone socks?
Silicone socks can make the fit tighter, reduce empty space and improve grip inside the foot pocket. Double K’s own sizing graphic states that silicone socks make the fit approximately 1 mm tighter.
Are these fins good for dynamic apnea?
Yes. Choose the softer S stiffness if your main focus is dynamic apnea, pool rhythm and repeated sets.
Are these fins good for depth training?
Yes. MS is the best allround choice for many freedivers, while M can make sense for stronger divers or those who prefer more blade resistance for depth-focused sessions.
Can I test the fit before ordering?
Fit is critical for this product. If you are unsure about size, contact us before ordering with your measured foot length, foot width and sock choice.
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