This is a package of DUBRO wheel collars generally used to secure the wheels on the axles on an airplane but can be used for other applications as well. Plated brass Uses a set screw to lock collar to the axle Twelve wheel collars Twelve 6-32 set screws One 1/16" allen wrench inside diameter - 5/32" outside diameter - 5/16" thickness - 7/32" btm 06/11/94 &