For practical shootings using the Tokyo Marui Hi-capa 5.1 at US$32.00 from RedWolf Airsoft... "Airsoft Surgeon's handy adjustable thumb rest reduces the chance for your supporting hand's thumb from touching the slide, thereby reducing chances of fouling when firing. Perfect for those of you with long dexterous fingers, this fully adjustable thumb rest allows to you adjust it whatever angle you like! Includes everything required to install onto your 5.1.

Requires drilling to attach onto the frame of your Hi Cap 5.1 therefore may require professional installation. For increased compatibility, please use consistent aftermarket branded parts, or consult your local gunsmith."