Abstract: A lock formed of a bar and a shackle whose legs extend into transverse holes formed in the bar. A rotatable bolt extends within and is completely concealed within the bar and overlaps the leg portions located within the bar. Aligned notches in the legs and bolt permit the bolt to be rotated into a position wherein peripheral portions thereof extend within the leg notches for locking the legs within the bar, and to a second position wherein the bolt notches align with the legs for transverse movement of the legs relative to the bar for unlocking. Locking means arranged within the bar permit selective manual rotation of the bolt. The shackle and bar may be formed of a saw resistant material to form a closed, saw resistant loop.