Material: Stainless+Aluminium Compatible Calibers:1911 Size: 1.69 in x 0.92 in x 1.4 in. Weight:2.5 oz This Item will not fit Commander (4.25 ) or Officer/Compact (4 or shorter) The bushing ID. Is .583" +-.0005". In general, this part is machined to fit any 1911 stock that has a barrel OD. between .577"-581". Even with a standard, stock size, the part may require some fitting depending on your individual and slide combination, but is machined to spec to fit onto a stock configured 1911. Installation: Start with the barrel and guide rod installed in the slide Insert spring and then insert spring cap. Depress the spring cap with thumb. With spring cap depressed, insert compensator and twist into place. Removal: Insert the back side of a 3/8” drill bit or dowel pin with a diameter of .399" to depress spring cap. Twist compensator counterclockwise to the 4 0’clock position Remove compensator. free spring cap! This spring plug is required for proper installation of any 1911 muzzle Brake Barrel bushing style compensator for Government (5”) barrel 1911 Autos.