The Apeks RK3 is a rugged thermoplastic rubber fin featuring an over-sized foot pocket to accommodate drysuit boots and a spring strap for easy donning and doffing.

The environment that an RK3 is used in will tend to dictate the size of fin that you need, for example do you dive in a warm environment wearing wetsuit boots, or are you walking across pebbled beaches and wearing a drysuit and rigid dry boots? Both forms of footwear may be a size 9, but will take up different amounts of space in the fin foot pocket.