Compact, adjustable receiver sight discs give choice of iris openings from .025" to .155" diameter. External “click” spring.
SPECS: Steel. ½" (12.7mm) diameter x ¼" (6.3mm) thick disc, 7⁄32" (5.6mm) - 40 thread. #4LS - 11⁄32" (8.7mm) long shank. #4ELS - 15⁄32" (11.9mm) long shank. #4 10-32 - 5⁄16" (8.7mm) long shank, fits Marble tang sight. #4 SS – 5⁄16" (8.7mm) long shank, fits Lyman #2 tang sight.
Catalog page 270