C4 Italy have been paving the way for carbon fibre dive fin technology since the 80s and in 2018 they've carried this tradition with the release of the much anticipated 300 Line aimed at greatly improving efficiency over previous C4 series.  The 300 Line foot pockets aren't tubby footpockets like what we're used to these days and C4 have opted away from this tradition because the volume of material used in the pocket defines it's drag, the more volume, the more drag, therefore more effort, less efficiency and shorter bottom times.
 
Further drag reduction results from both the shape and the form of these footpockets.  They're designed to fit super tight at first which will mould them to form-fit your feet, this results in a very 'cosy' footpocket and the sharp lips of the footpocket tuck nicely against your wetsuit sock, meaning no water can enter the footpocket - a major contributor to fin-drag.  A tighter fin allows greater efficiency because all force it directly applied to the foot pocket and then the fin, softer foot pockets are less efficient in that part of your kick force it lost in the soggy rubber.
 
Blade positioning draws influence from C4's history making the world's best carbon bicycles.  Utilising their knowledge of power application through the leg and feet they're built these fins to create load in between the toes and metatarsus, this is where the foot generates the most force, efficiently.  A 20mm sleeve exists on the underside of the foot pocket to distribute load to the pocket evenly, not just through the mounting screws, not only increasing efficiency but spreading load, therefore lessening strain-induced degradation.
 
C4 300 Line footpockets are designed to work with all 300 lines blades but if you want to use a universal blade [other C4 lines, or DiveR for example] we offer an adaptor kit so you can enjoy the efficiency of the 300 series pockets with your favourite blades.
C4 300 Line Fitting Instruction Manual
 
 C4 300 Line Black Footpocket Features:
 
  
300 Line Compatible - fits C4's new 300 line blades and most other fins with use of the adaptor kit.
  
Low Volume and Drag - form-fit design allows the pocket to mould to your foot, creating the most snug fit possible.
  
Lightweight - A 300 foot pocket size 40-41 only weighs 315gr.
  
3° Integrated Angle - More angle = more preloading, C4 have found that amplifying native blade angle combats the loss of power associated with softer, more effeciant blades.
  
Sold in pairs