Sleeves, Jointing, Self-soldering, No.3. Each sleeve is made up of two copper tubes ,flared at the ends to enable the easy insertion/ positioning of wires and joined at the centre with solder covered with a flammable wax. A small red 'blob' of striking material is at the centre of each unit. These were used by the Special Operations Executive and American Office of Strategic Services for joining wires during sabotage and demolition work. When struck against a rough surface or the side of the issue box, the wax covering would ignite and heat up the solder which when cooled would fuse the inserted wires together. These come in 10s, packed in an oversized matchbox type container with the original instruction leaflet. In excellent, unissued condition. We have just discovered another pack in our stores.Condition is the same as those photographed. Stock code E20174.