Aluminum gauge keeps barrel placement consistent during X"Xmill and fitX"X procedure. Hole in gauge lets you place a dial indicator on barrel to make sure that it remains in proper alignment while you check for proper lock-up. Mfg: Egw SPECS: Aluminum, black. 3" (76mm) wide, 1" (25mm) high. Slots are .362" (9.1mm) and .368" (9.3mm).
