The material of the BM30 fin: A light and reactive technopolymer, unique to date, which offers performance similar to carbon fibre-based composite, while eliminating the well-known problem of material fragility. The technopolymer used is so elastic and has such a high shape memory that - in an absurd demonstration - if we were to look at the blade after rolling it up on itself, once released it would still have its initial geometry, without any permanent structural deformation that could compromise its performance. The geometry of the BM30 blade: The blade of the SEAC BM30 fins is inclined by 30. This more accentuated angle is ideal both to facilitate surface finning and to support the natural inclination of the ankles when diving. In addition, the ultra- thin, differentiated profile creates optimal flexion. The small stabilisers placed at the end of the blade, at the point of greatest water flow, prevent the fin from drifting sideways without compromising the correct flexion of the blade. Like the successful Motus series, the BM30 foot pocket is made of two different materials, a stiffer one on the sole for stability and a softer one on the upper for maximum comfort during prolonged use. The BM30 foot pocket is optimised to accommodate blades angled at 30. The short water rails enable the technopolymer of the blade to express all its reactivity and flexibility.