Lyman long shank apertures. Fits Redfield and possibly Williams. 7/32-40 or 12-40 thread. Will fit your Lyman tang sight too. All different aperture and OD dimensions please see below. All are NOS. Shipping is lettermail in a reinforced envelope. No tracking. Aperture size x outside diameter. $12 ea shipped. - .038”x .324”. -.046”x .321”. -.048”x 321”. -.050”x.321”. -.054”x.321”. -.062”x.321”. -.100”x.321”. $18 ea shipped -.026”x.383”. -.038x.383”. -.043”x.383”. -.055”x.383”. -.095”x.383”. $22 ea shipped. -.037”x633”. -.054”x.633”. -.062”x.633”. -.090”x.633”. -.035x.698”. -.054”x.698”. -.095”x.698”. Below are sold -.143”x1.004”. -.043”x1.310” *Possibly Merit brand Have multiples of some, OD looks to vary but only a few thousands of an inch for each respective size.