APEX FIN RK3 HI-VIZ LG. 

Designed in collaboration with the US military and renowned for outstanding performance and reliability, the Apeks RK3 Fins are a rugged thermoplastic rubber fin featuring an oversized foot pocket to accommodate drysuit boots and a spring strap for easy donning and doffing. The RK3 is available in three sizes: Medium, Large, and Super. 

The fit of the boot will change depending on the environment in use. For example, using a boot with a thicker millimeter will take up more space than a boot with less.