Poland also had the TK tankette (also known as the TK-3) which was based upon an improved chassis of the British Carden Loyd tankette. The 575 TK/TKS tankettes formed the bulk of the Polish armored forces but as their armament was limited to machine guns, their combat value was limited. They suffered heavy losses during the Invasion of Poland. Only the handful of tankettes armed with 20 mm guns had a fighting chance against the enemy tanks; in one instance on 18 September 1939 a 20 mm gunned TKS destroyed three German Panzerkampfwagen 35(t) tanks.