The fixing nuts on these top mounting are designed to be captive in the mounting but over time they become corroded so when removal is attempted they can break loose.
A uniquely shaped extension bar eliminates the spring restriction and attaches to a double sided socket to remove the fixing underneath the mount where access is poor
OEM fixings can either be 6 or 8 sided nuts which is why the tool includes a double sided socket
3/8"D female square with a 1/4"D male extension bar 80mm plus a 6 point(sided) and 8 point(sided) socket with 1/4"D female square