rear caliper

Hey Gang, What size Allen key should I use to turn the adjustment screw on the rear calipers? Feeling pretty defeated after I spent almost 2 hours replacing the pads and rotor on one wheel only to basically feel like I stripped the adjustment screw. I had undo everything and install the old...

Working on rear brakes today. Replaced passenger side rotor and pads with a bit of a fight with caliper pins and carrier bolts. Found inserting pads surprisingly difficult BTW, any ideas why? Was able to retract caliper piston by hand just by using an open ended spanner (19mm) in the notches...