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 4-40 set screws One .050" allen wrench inside diameter - 3/32" outside diameter - 1/4" thickness - 3/16" btm 06/11/94 &