Calk-Inâ„¢ Mechanical Bolt Anchor Print The Calk-In is a pre-assembled precision cast calking type machine bolt anchor which can be used in concrete, block and brick. It can also be considered for stone. The Calk-In consists of an antimonial lead alloy calking sleeve and a Zamac alloy internally threaded expanded cone. This anchor is not recommended for use in overhead applications or for life safety. Read Less