Hollow Spy Bolt

This 5/8" diameter steel bolt has been hollowed out, and has a threaded, removable head. During the Cold War, devices like these were used to transfer messages and microfilms between two individuals without the need for them to meet. The bolt was left in an inconspicuous location, such as on a bridge or automobile where it would be replaced with an original bolt.
This item was featured in Make Magazine, issue 16 “Spy Tech”, and is now available for sale here by the author. Available with either a right or left hand thread on the bolt’s head…please specify when ordering. The left hand thread offers a bit more security as it uses an unnatural opening movement.