RC Model Engine Clutch Replacing Collet Coupler Shaft 5mm x 3.18mm Product Name : RC Boat Collet Coupler Shaft;Thread Size : 7mm x 8mm/0.28" x 0.31"(D*L) Collet Hole Dia. : 3.18mm/1.25";Untheaded Motor Shaft Dia. : 5mm/0.2" Total Size : 32 x 10mm/0.13" x 0.4"(L*Max. D);Materials : Stainless Steel Net Weight : 15g Package Content : 1 x RC Boat Collet Coupler Shaft