In years 1929-1939 Polish Army have designed, produced and tested many versions of tankettes. One of the most advanced of them was TKS, mass-produced since 1934. It's project included thicker armor (10mm all-around), improved suspension and better weapon placement. TKS was armed with single 7.92mm Hotchkiss MG or 20mm gun. The first version was a mobile support used against infantry, second one could be used as a anti-vehicle weapon. Because of low-calibre and lack of firepower TKS was often outmatched by the Germans.
In 1939 tankettes were considered quite obsolete but formed the bulk of Polish armored forces. With over 400 combat-ready, mostly TK-3 and TKS, these vehicles were most numerous in the September Campaign.
Only handful of TKS were reequiped with 20mm guns – depending of the source the number oscilates around 15-24. Some of the tankettes were put to good use by skillful and talented crews, destroying many German tanks and vehicles. One of the most famous TKS commanders was Roman Orlik, who single handedly took out of action three enemy PzKpfw 35(t) in one fight.