The GK Tactical STI nylon grips for the Tokyo Marui hi-capa series is a light weight grip designed to work with that particular gbb pistol series. The grips also feature a fair amount of checkering for added grip when shooting without gloves.
Tokyo Marui Hi-Capa 5.1
x1 GK Tactical Nylon Grips for Tokyo Marui Hi-Capa GBB Series - Black
x1 Screw pack