K4 Race Paddleboard SUP Fin US Box 21cm and 24cm
£39.99
Swept back SUP race fin.
45 degree rake so you don’t have to worry about weed or debris.
Foil optimised for paddling speeds, but taking many pointers from our speed windsurfing fins. In fact I stuck this yellow fin in my windsurf and did 48mph on it!
Dynamic Flex material gives more grip, better tracking and more speed than stiffer materials.
An already proven SUP race fin can also be used on windsurfers with US box as a weed fin.
Available in a choice of two sizes:
- 24cm – 255 area – 260g
- 21cm – 210 area – 215g
Comes with Nylon Us box plate and screw as shown.
| Brand | K4 |
|---|---|
| Construction | Plastic Composite |
| Size | 21cm, 24cm |
| Fin Box Type | US Box |
CLICK AND COLLECT:
- If you are located in the UK at the checkout you will be able to select to collect from our Store in Gosport.
COURIERS WE USE:
- Royal Mail for small and medium parcels
- Parcel Force for medium items like kites, harnesses and iSUPs
- UPS, DHL & Parcel Force for larger items like booms masts and boardLarge items such as boards, booms and masts will be delivered in 3-5 days as bigger vehicles are required by the couriers and can induce delays.
DISPATCH: All items are dispatched from our Gosport Store and will experience a 24hr delay where we are closed on Tuesdays. Any orders taken after 1pm on Friday and over the weekend will be dispatched on Monday.
EU and Worldwide Postage: EU and Worldwide items are priced without VAT. Our webstore is not setup for orders outside the UK but if you would like to purchase from us please email us with your details and we will reply with a postage quote. Payment is required by Bank Transfer.
RETURNS: Use the address below for returns. If a refund is required we will refund only the value of the item(s) and not the postage. Returns must be made within 14 days unless the item is deemed faulty. Please include the original shipping label as this will have the order reference and you name on it.
RETURNS ADDRESS:
Andy Biggs Watersports
103 Bury Road
GOSPORT
PO12 3PR
DAMAGED ITEM: If an item is damaged in transit you must notify the us immediately upon delivery and let us know as soon as you can.
Related products
Starboard Bio Resin Green 18.5cm SUP Paddleboard Fin US Box
Temporarily out of stock, please call - 023 9258 2614
Starboard fins for Stand Up Paddle boards are designed to ensure flex and strength, while reducing weight as they are made with Net Positive technology.
This construction is developed from the combination of fishing nets recovered from the Ocean that are recycled along with other materials to increase the performance of the fins.
You can choose from several options with different sizes. This specific fin model is 220 mm in 8.6", but in our store you can choose from several options with different sizes.
These Starboard fins manage to improve the behavior of SUP boards in different situations. Remember to use larger fins for better tracking and speed, and smaller fins for more maneuverability.
Suitable for all boards of the Starboard range and other brands with the US BOX fixing system.
Starboard Dol-Fin 22″ Paddleboard SUP Fin
Only 1 left in stock
Starboard fins for Stand Up Paddle boards are designed to ensure flex and strength, while reducing weight as they are made with Net Positive technology.
This construction is developed from the combination of fishing nets recovered from the Ocean that are recycled along with other materials to increase the performance of the fins.
You can choose from several options with different sizes. This specific fin model is 220 mm in 8.6", but in our store you can choose from several options with different sizes.
These Starboard fins manage to improve the behavior of SUP boards in different situations. Remember to use larger fins for better tracking and speed, and smaller fins for more maneuverability.
Suitable for all boards of the Starboard range and other brands with the US BOX fixing system.
K4 Futures Symm Pair Side Fins (x2) for Surfboard Paddleboard SUP Windsurf
In stock
K4 Futures Assy Pair Side Fins (x2) for Surfboard Paddleboard SUP Windsurf
In stock
Red Paddle Co US Box Flexi SUP / Windsurfing Fin
Temporarily out of stock, please call - 023 9258 2614
K4 Ezzy Assy 2 Degree Fins Slot box pair
In stock
K4 Ezzy Assy 2 Degree Fins Slot box pair
The Ezzy Asymmetric fin! More power, more drive, more speed, less drag.
The Ezzy front fin has a similer template to the Stubby but with a wider chord. A fully asymmetric foil with a radiused front and slightly positive inner foil to aid flow at high speeds. Choose a smaller fin size for less drag, same power. Great for huge gouging hooky cut backs!
SOLD AS PAIRS
K4 FCS Surf Assy Side Front Fin Pair
In stock
These fins are Asymmetrical.
"We’ve had a unanimous thumbs up for the K4 Fins SUP surf fins; from the Bluesmiths team using them in Maui perfection, to the likes of big wave ripper Finn Mullen in Ireland, through to those in the UK having their first experience of Stand Up Paddling.
We’re excited to bring you a substantial range of sizes in the K4 shop to tune your board for every wave. Our asymmetric front fins are available in 8, 10, 12, 13  and 14cm." - K4 Fins
These K4 surfboard FCS fins are perfect for directional kiteboard surfboards, normal surfboards and wave sups. Buy the 10cm ones for a looser feel or for smaller boards and buy the 12cm for pretty much everything else.
K4 3SW Freeride Freestyle Freewave Windsurfing US Box Fin
In stock
K4 3SW Freestyle Freewave Freeride Windsurfing US Box FinÂ
The 3SW freestyle-wave fin. Developed with help from the Official Test Centre Weymouth. A fin that will give you amazing speed and control, secure and loose carving on the fast flats or choppy waves. The material is K4’s ‘Super Stiff’, the ideal composite for freestyle-wave fins; great reflex, stiff enough for excellent acceleration and direct response, enough flex for speed, grip and control. The 3SW also works great in big wave boards.
K4 FCS Thruster Fin Set for Surfboard Paddleboard SUP
In stock
"We’ve had a unanimous thumbs up for the K4 Fins SUP surf fins; from the Bluesmiths team using them in Maui perfection, to the likes of big wave ripper Finn Mullen in Ireland, through to those in the UK having their first experience of Stand Up Paddling.
We’re excited to bring you a substantial range of sizes in the K4 shop to tune your board for every wave. Our asymmetric front fins are available in 8, 10, 12, 13  and 14cm." - K4 Fins

Reviews
There are no reviews yet.