7.4V 600mAh 30C LiPo for HPA Engines (JST) adapter On the top are differently

On the top are differently spaced holes and adjustable pins

CNC Aluminium Hopup Arm For TM AKM/AKX GBBR

It is incredibly expensive to machine a grip from 1 block of aluminium

Possibly also fits other platforms

Depending on your particular hop-up chamber

7.4V 600mAh 30C LiPo for HPA Engines (JST) adapter On the top are differentlyHigh discharge battery for HPA engines. This little but powerful LiPo battery has twice the capacity of usual HPA batteries, and with new high discharge materials. This ensures a significantly higher total shot capacity, especially with engines that rely on higher amperage to function, or in cold weather. The battery measures 80mm x 16mm x 10mm and can easily fit in grips, stocks or other small places. The battery comes with JST plug for engine