Easy installation, just trim, and glue the mount to the fiberglass fuselage. Also usefull as an additional reinforcement for plywood firewalls. Use high strength epoxy only. B20 Hacker B20 w/gearbox or direct, Mega 1615/x 1 1/8" diameter, 1/32" thick (28mm x 1mm) B40 Hacker B40 w/gearbox or B50 direct, Mega 22/x/x, AXI 28xx/xx 1 3/16" diameter, 1/16" thick (30mm x 1.5mm) B50 Hacker B50 w/gearbox 1 3/4" diameter, 1/8" thick (45mm x 2.5mm)