Advances in tank design, armour, and engine technology allowed tank designers to increase the capabilities of tanks significantly, allowing vehicles to undertake multiple roles on the battlefield. This could be accomplished without always resorting to heavier designs, although weights did gradually increase. High explosive anti-tank (HEAT) ammunition was a threat to tanks and could penetrate steel armour thicker than was practical to put on a tank. Advances such as the British-designed Chobham armour limit the effectiveness of weaker HEAT rounds, but the vulnerability still remained.