Fits handlebars with 1" (25.4mm) outside diameter & 14mm to 19mm non threaded inside diameter. Used to install handlebar-end (bar-end) mirrors to the end of the handlebars. Can also be used as regular handlebar end plug, when no mirror is installed. Adapters bolt inside the handlebar. Includes installation hardware. - Mirror mount size dia. 30mm - CNC aluminum - Hex socket bolt (M6 x 45mm) - Sold in pairs - Black anodized finish