The contact fuse is an electric shock fuse of instantaneous safety type. The fuse consists of four reaction contacts, one each on the rudder of the missile, and a PIM. The reaction contact closes the electrical circuit of the PIM when the rocket rudder contacts the target. The contact consists of a steel knife 3 and an insulated wire 2 wrapped around the knife. The knife and wire are located in the rudder groove 1 and filled with compound 4. The wire is connected to the electrical circuit of the PIM. The knife is soldered to the rudder, which acts as a "mass" - the second conductor. In the event of a direct hit from the missile to the target, the insulation of the wire will be destroyed by the knife and the electrical circuit of the PIM flame retarder will be closed as a result. The purpose and principle of a PIM contact fuse is the same as that of a non-contact fuse. The only difference is that a PIM contact fuse does not have a liquidator.