need help with ground controls

does anybody kno wut size allen key is used to loosen the screw on the ring? iv tried a few of my friends keys but they are just a lil too small and iv heard repairing a stripped bolt on these is a pain in the ass. hoping sumone here can help. thanks

if the fit is not snug then dont use it cause you dont want to round out the inside. Im not sure of the size but I bought a set of allen keys especially for that purpose. Cost like 9 bucks. Thats the only thing I dont like about the ground controls is the 1 perch design. other than that they’re great.

4.5mm or if you can’t find that it’s a 3/16