Fine-tune your Marble tang sight for specific shooting situations by installing the perfect-sized aperture. ½" and ¾" diameter apertures in six hole sizes make it easy to obtain the best accuracy and target acquisition for long and short range, hunting or target shooting applications.
SPECS: Steel, blued finish. ½" (1.3cm) diameter apertures - .055" (1.4mm), .076" (1.9mm), and .102" (2.6mm) hole sizes. ¾" (1.9cm) diameter apertures - .032" (.813mm), .043" (1.1mm), and .055" (1.4mm) hole sizes. 10-32 thread fits Marble’s Tang Sights.
Catalog page 277, 278