Improved Looks & Function
These excellent looking Allen-head screws will dress up any Ruger
Mk I or Mk II pistol plus give positive wrench engagement to help
prevent stripped-out grip screws. Same diameter head as the
standard screw, fits flush on all factory and aftermarket grips.
Big Book Catalog, Issue:66, Page:221
New Product Supplement, Issue:552, Page:002
SPECS: Steel, blue or Nickel plated. 6-40 tpi, .250" (6.3mm) diameter head,
.325" (8.1mm) long. 3/32" Allen head.