This item was made and used by a foreign intelligence service hostile to Canada. It was designed to conceal a spool of film ostensibly from a contact to his/her intelligence officer handler. Its design and appearance are such that it could be placed in certain locales (construction sites and the like) without arousing any undue attention. It could then be retrieved without the parties having to make direct contact.
A hollow steel bolt containing a metal canister with film spool.