Compatible with the Tokyo Marui M14 platform. 

Also compatible with all V2/V3 gearboxes with some minor modifications to the gearbox shell (drilling out the bottom of the lower ARL post). 
This is beneficial as the V7 ARL lower post is much longer so the ARL will hold in position much more readily. 
A slot can also be cut in the end of the post using a thin stone-disc on a Dremel so the ARL can be activated from the outside of the gearbox. 

This modification requires a moderate amount of skill and technical knowledge so care must be taken.