Initially, they were armed with two machine guns on a single mount and were able to carry up to 22 mines.

Seized by the Germans in 1939, they were briefly commissioned by the Kriegsmarine as FM1 and FM2, before being transferred to the Romanian Navy in 1941 as V5 and V6.

The two boats were captured by Soviet forces in September 1944, their subsequent fate remaining unknown.

[1][2] V5 and V6 laid several mine barrages on the Chilia branch of the Danube Delta against Soviet warships during Operation München, however these proved to be ineffective.

[3] During the summer of 1943, joint German-Romanian forces carried out a sweeping operation across the Danube Delta, over 50 mines being swept as a result.