Product Descriptiongood bore, Conversion barrel for unknown 11mm caliber handgun. 7 5/16 inch barrel has a 10.96mm outer diameter. Fire blued locking collar with two locking nuts. The collar has a slot which appears to be for sliding over a front sight blade, the open slot being about 2.73mm in width. The collar then turns to lock behind the blade when installed. The opening for the length of the blade measures 12.67mm. Unmarked except for the RWS logo on the collar. Used, in over all good condition. From the collection of Dr. Geoffrey Sturgess.