This bolt, with a red and white "evidence" label, was recovered from bucket of dried cement on roof of cellblock after 1962 escape from Alcatraz.
Metal, tape. H 8.0, DIAM 3 cm
Golden Gate National Recreation Area, GOGA 396
Bar-spreader, made by inmates involved in the 1962 escape attempt.
Galvanized metal. H 10.5, DIAM(of nut) 1.6 cm
Golden Gate National Recreation Area, GOGA 397