Design work upon a simple flamethrower for the Polish underground, suitable for clandestine production in ordinary workshops, of readily available materials, started in 1942 on request of the Home Army main headquarters.

There were several designs produced, of which the most popular was the K pattern, becoming a sort of standard weapon of the Polish underground.

[2] The K-pattern flamethrower appeared a successful weapon, considering its primitive design and conditions of manufacturing.

Its main flaw was that the air pressure decreased during operation, and so successive bursts had a progressively shorter range.

The weapon could be refueled by fuel carriers and the compressed air bottle replaced with a new one, in a procedure that took about 4 minutes.