The PMR-U is a Yugoslavian anti-personnel stake mine. The mine was apparently not mass-produced, but built in small numbers at a number of different locations.
The mine has a small plastic main body with a large seam in the middle. Internally the mine has a 100 gram main charge around which a mixture of Plaster of Paris and steel fragments is poured to form a fragmentation liner. The mine uses a number of different commercial explosives, with the result that the mine becomes unstable over time.
The mine is found in Bosnia and Croatia.
Specifications
References
PMR-U mine Wikipedia(Text) CC BY-SA