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SKU: 5513
Reg. Price: $139.95
Our Price: $112.20


IST Propulsion Rubber Fins

F4 Propulsion represents the latest evolution of Military-style Fins from IST.

Based on IST's iconic and military favorite F-1, the F4's wide blade design is slightly shorter – however, there is no power shortage here. That’s because of the expanded width rubber blade which incorporates unheard-of flexibility. Even more thrust is attained by 3 deep vents which force water backwards, emulating the effect of three synchronized turbo-powered water jets.

The F-4 is excellent for open water dive missions, but also shows its skill in assisting diver- maneuverability within confined spaces. As you would expect and demand of a military fin, the F-4 is durable and long-lasting; compatible with IST’s famous Universal clamp stainless steel coil spring fin strap. There’s a reason U.S. Military Personnel have made IST's exclusive F1 Deep Sea Scuba Diving Military Rubber Rocket Fins their number one choice. The F-4 is following the tradition, already a favorite with the U.S. Navy.


  • The fin is not only useful in the ocean but also capable of handling technical dive missions in underwater confined spaces.
  • The choice of material makes Propulsion durable and long lasting IST stainless steel spring fin strap compatible (item no.: FS10)
  • The fin is useful in open water but also capable of handling dive missions in confined spaces.
  •  Propulsion represents a new generation of rubber fin. The fin is designed slightly shorter but no power is lost through its wider blade rubber’s unmatched flexibility. In fact, more thrust is gained by 3 deep vents, which force water backwards, mimicking the effect of the water jet.
  • Durable and long lasting.
  • Sizes: M (US 7-9 EUR 36-38), L (US 10-11 EUR 39-42), XL (US 11-13 EUR 43-36)


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Question asked
on 4/4/2013
Description indicates this rubber fin is short but has a wide blade. Can you give me the approximate measurements of fin (back of foot pocket to blade front and width across foot pocket as well as front part of blade)? Would this fin work good for ocean dives with strong currents, or would there be an excessive amount of exertion involved due to fin being shorter? Most of my diving is done in cenotes and caves. Fin looks like it might be suitable in tight spaces and for underground river type diving; but I would sure appreciate having some imput as to how these shorter fins would perform in open water dives. Thank You!!
Answer by Bill
on 4/9/2013
Hello, Got your phone message and just got the answer for you: Thank you for the email. Here are the measurements for a size large, they will slightly vary based on the size. back of the fin, from heel to blade tip: 20.5" blade (not including foot pocket): 9.75" width across foot pocket: 4.5" width across blade: 9" To answer the other questions. This fin is great for tough currents due to the vents, it will not cause excessive exertion. It is perfect for tight spaces, including cenotes and caves. They will perform great in open water dives.