Perfect!!! - Daniel Defense Buttstock, Pistol Grip & M-LOK Vertical Foregrip Combo

The fit is incredibly tight, in fact it may take a few attempts to get it to slide on. I would suggest using a screwdriver to compress the pin from the inside a few times to loosen it up before trying to pull it into place. Also a second set of hands will help you save time and frustration trying it alone. The first one took me about 40 mins of struggling and using different angles. The second one I asked my wife to push the tube into it as I was holding down with all my might on the release lever and it fell right into place.