Compatible with all TM HK416 and HK417 base guns. 
Requires the matching DEVGRU base plate, screws and motor adjustment plate to work. 

When inserting the base plate screws, extreme care should be taken to match the screw thread to the existing grip thread. 
The screws will cut a new thread if forced in which will break the grip very quickly. These screws should be tightened slightly past finger-tight (around 0.7Nm). Over-tightening the screws will cause the base plate and screw supports to break immediately.