HiKOKI 956930 Chuck Sleeve 12 x 3/8" for compatible Hitachi and HiKOKI routers and trimmers. This replacement reducing sleeve fits a 12mm router collet and allows the use of 3/8" (9.53mm) shank router bits. Suitable for replacing a worn, damaged or missing original chuck sleeve and manufactured to the correct specifications for precise bit location and secure clamping.