For use with the William's Target Globe front sight, these steel attaching bases either fit a rifle's 3/8" dovetail or use screws to mount to the barrel, forming a solid foundation upon which to mount the front sight. Blue finish. Notes: Globe front sight comes with 10 inserts and is .545" high not including the mounting base.Mounting base must be purchased separately.Mounting base heights are listed in the description for each. Radius dimension in the description refers to the barrel's radius.