The C4 MB fin project aims to update our medium-high range of carbon blade fins, with particular attention to respecting the traditional canons of the technique. To develop these fins we started from the foot pocket. The MB Fins feature the new 250 foot pocket, a direct derivation of the previous 300 model but with unique features

250 Footpocket:
Thanks to the use of a 75 ShA TPE polymer overmolded onto a rigid base, the 250 footpocket optimally transmits energy from the foot to the blade, resulting in highly efficient fins. Furthermore, the study of geometry has allowed the use of minimal thicknesses, reducing the weight of the 250 liner in size 41/42 to just 250g.
Performance: The reduced mass (weight) of the 250 liner minimizes the energy required for movement, thus allowing the user to significantly save energy and consequently reduce muscle fatigue. In fact, the connection between the shoe and the blade, thanks to the internal sole, is rigid and solid, and transmits force to the blades with high efficiency. The blade attachment to liner-less shoes, developed by C4 in 2006, allows for elastic flexion of the blade along its entire length.
Anatomy: The 250 liner’s pre-shaped 3° anatomy makes it particularly comfortable to wear. The thin layers adapt the shape of the upper to the foot, without painful constriction.
Material: The polymer used for the 250 liner is particularly elastic and allows for an easy and simple fit, improving comfort. The insole provides a rigid sole with a comfortable upper.
Transport: The 250 liner has a simple blade attachment via a single sturdy M6 screw. The assembly and disassembly of the shovel is quick and easy and its size is optimal for air travel.

MB blades:
The key factor that increases performance is the new dedicated “Reverse Parabolic” lamination. A parabolic curvature that, instead of having the part with greater flexion at the tip, presents it near the foot. A complete reversal of concepts and an evolution of what our DPC (Double Parabolic Curve) blades were.
The dedicated lamination significantly changes the mechanical behavior of the fin. La superficie che genera la spinta di reazione risulta infatti essere più estesa rispetto alla parte di superficie che genera resistenza idrodinamica. In this way it is able to produce greater elastic deformations and greater propulsion. The fin thus becomes a natural extension of the leg and not a simple mechanical appendage on which to exert force. The advantage is that it’s possible to use stiffer blades, which therefore offer greater performance, but with the same effort as using lighter blades.
By exploiting this feature, we’ve increased relative performance. It is as if a “+” had been added to the expected hardness levels. This is because, when flexed in the hand, an MB 25 is stiff and pushes as much as a standard 30 while weighing the same in the water as a 25. This results in higher bottom starts, acceleration, and speed.
The MBs have new curved water rails that improve water containment on the blade and reduce vortices on the outer edges. Water rails, first introduced by C4 in 1993, have always served the purpose of keeping water on the blade parts that generate reaction thrust.
The MBs have a greater extension of the thrust plane, and for this reason the water rails are integral, from the foot pocket to the tip of the blades.
Without foot pockets like the 250s, all this would not have been possible. As always, it’s the combination of shoe and blade that produces the result.
The carbon blades all have a matte surface finish.