Hoods are available in Small, Medium, and Large diameter. Window-style hood features light-admitting side cutouts for use with fiber optic front sights.
Big Book Catalog, Issue:66, Page:282
New Product Supplement, Issue:602, Page:014
SPECS: Hoods - approximately 1-1⁄8" (3.1cm) long. Small - .555" (14mm); Med. - .630" (16mm); Large - .708" (18mm) I.D.