UMP-2 is a booby trap fuze designed for the tripwire initiation of mines and demolition blocks by radial pull. The principle of operation is similar to a Russian MUV. A spring-loaded striker is housed in the tubular fuze body, which has an integral detonator assembly. Two pins pass through the striker where it protrudes from the fuze body: the upper one is designed for safety and the other for firing, though they are interchangeable. The end of the fuze is sealed by an O-ring with a metal washer on top; the lower pin bears on the washer to compress the seal. A plastic collar around the fuze body; this is split down the side and has a slightly tapered male M10 × 1 thread.
More than one tripwire can be used with UMP-2; since the fuze body is free to rotate within the plastic collar, it will turn to face the direction of pull before the pin is withdrawn. The striker retaining pin also includes a section bent around the neck of the striker to hold it safely in place while the trap is set up. The fuze body is normally unpainted and without markings; the collar is made from olive green plastic.
The fuze is fastened into the parent mine or demolition block by screwing in the outer collar, which is compressed onto the fuze body by the tapered thread as it screws in. One or more tripwires are attached to the lower (firing) pin and the upper (arming) pin then withdrawn to arm the assembly. The lower pin is rotated by 180° to release the kink from around the striker and allow it to be withdrawn more easily; without this action, considerable force would be needed to extract the pin.
When the wire is tripped, the retaining pin is extracted, releasing the striker onto the stab-sensitive detonator assembly.