Replacement Bushing Spacer Pack, of the Citadel Series, is included in each Citadel Sliding Shower Door Kit, but this replacement pack is available if needed. Two each of three different sizes are used to help fill the holes drilled in glass and prevent slippage. Two Bushings have internal diameter of .312" (8 mm), two at .445" (11 mm), and two at .510" (13 mm), with all having an outside diameter of .720" (18 mm). The appropriate size is selected to help fill the holes drilled in glass for the Hangers to help prevent slippage.