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MB Fins

The MB project objective has been to renovate our medium-high range of fins featuring carbon fiber blades.


At C4, the 200 series fins are considered the most technical while we think these MB fins are our best interpretation of the concept of traditional carbon fiber fins.


Foot pocket 250

For the development of these fins we started from the design of the foot pocket. MB Fins feature the new 250 foot pocket, a direct derivation of the previous 300 model.


Thanks to the use of a TPE 75 ShA polymer overmolded on a rigid sole, the 250 foot pocket transmits energy from the foot to the blade in the best possible way, resulting in highly efficient fins.

The design of the geometries has allowed to use minimum thicknesses resulting in a reduction of the weight of the 250 footpocket in size 41/42 to just 250gr.



The reduced mass (weight) of the 250 footpocket minimises the energy required for movement, thus allowing the user to save considerable energy and consequently reduce muscle fatigue.

The connection between the foot pocket and the blade, thanks to the internal sole, is rigid and solid, and transmits the force to the blades efficiently.


The assembly of the blade on the footpocket without side horns, already created by C4 in 2006, allows an elastic bending of the blade along its entire length.



The 3° pre-shaped anatomy of the 250 makes it particularly comfortable to wear.

The reduced thicknesses fit the shape of the upper to the shape of the foot, without painful constraints.



The polymer used for the 250 foot pocket is very elastic and it allows for an easy and simple fit, thus improving comfort. The insole allows to have a stiff footpocket in the sole area but comfortable in the upper.



The footpocket 250 features a simple assembly of the blades thanks to a single sturdy M6 screw. The assembly and disassembly of the blade is quick and simple and the overall dimensions are optimal in case of air travel.


MB fin blades

Despite a reduced weight, having such a solid foot pocket on which to apply the blades has proven to be an ideal solution to increase performance.


In MB fins, the major factor that increases performance is the new dedicated “Reverse Parabolic” lamination; a parabolic curvature which, instead of having the part with greater flexion at the top, it is near the foot. A complete reversal of concepts and an evolution of what our DPC (Double Parabolic Curve) blades had.


This dedicated lamination significantly changes the mechanical behaviour of the fin. The surface that generates the thrust is in fact greater than the surface that generates hydrodynamic resistance, thus producing greater elastic deformations and greater propulsion. The fin becomes a natural extension of the leg and not just a simple mechanical appendice on which to exert force.

There is such a big advantage that it is possible to use stiffer blades, therefore with greater performance, but using the same effort normally used with lighter blades.


Taking advantage of this feature we have raised the relative performance. A “+” has been added to the hardnesses. This is because, flexed in the hand, an MB 25+ is stiff and pushes as much as a standard 30 while weighing in the water like a 25. Restarts from the bottom, accelerations and speeds are thus higher.


MB fins feature new rounded section water rails that improve water containment on the blade and reduce water vortexes on the outer sides. The water rails, introduced by C4 for the first time in 1993, have always kept the water on the parts of the blade that generate the thrust. The MB feature a greater thrust surface and, for this reason, the water rails are integral, from the foot pocket to the tip of the blades.


Without shoes like the 250 none of this would have been possible. As always, it is the combination of shoes and blades that produces the result.

MB fins are available in two versions:

  • – The MB001, short 80cm blades with black graphics.
  • – The MB002, long 90cm blades with white graphics.

The carbon blades all feature a matte surface finish.

MB fins are named after their creator: Marco Bonfanti, who wanted to personally sign his new fin project featuring the “Reverse Parabolic” curved blades.

C4 MB001



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