The Apeks RK3 HD is the latest model in the RK3 range. It is made from a higher density (HD) than the standard RK3, which makes the fin stiffer and with negative buoyancy, ideal for wetsuit diving. The Apeks RK3 HD 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 RK3 HD is available in four sizes: Small, Medium, Large and Super. We didn't give the RK3 HD fin a shoe size range as this can be very misleading. The environment that an RK3 HD 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. Based on one of the first vented rubber fins sold in North America and popular among military and professional divers. Compact, and ultra-rugged for use in harsh environments. Improved foot pocket with spring straps for ease of use with cold hands or thick gloves. The design has been the standard gear issue fin for military, special ops, coast guard and public safety divers for decades. Short wide blade provides maximum forward thrust while maintaining great manoeuvrability. Vented blade design reduces resistance on the upstroke and enhances thrust on the downstroke. The vents also eliminate vortexes that can occur along the back of the blade much in the same way split fins eliminate the vortex. The blade material designed to hold up in the toughest environments, temperatures and abuse. Two large grommet holes designed to fit most karabiners for easy storage of the fins while accessing the dive site. Spring straps as standard. Custom designed buckle holds spring straps in optimum position. Simple push pin design allows simple replacement of springs if necessary.