It uses a bright 1

especially if you are working on Frenzel equalization and want visible balloon feedback

a tag is often placed at the bottom plate or target depth

stiffness and foot pocket size matter more

Double K - Delfit Monofin Tauchcomputer It uses a bright 1Double K Delfit Monofin The Double K Delfit Monofin is a high performance carbon monofin built for freedivers who want powerful propulsion, precise blade response and a secure foot pocket connection. The Delfit system combines a high elasticity carbon blade, autoclave molded construction and Double Ks dedicated Delfit foot pockets. The result is a responsive monofin for dynamic apnea, CWT, depth training and serious monofin technique work. Available