The tank is a major part of all large armies today. Tanks have replaced the cavalry everywhere and do the things that soldiers on horseback did in the past. Most modern tanks are of the heavy or Main Battle Tank type, able to fight other tanks. Compared to older types MBTs are very heavy (Russian MBTS being about 40 tons and Western around 60 tons) with a 120 mm (Western) and 125 mm (Russian) calibre cannon and 2-3 machine guns. Marines and other specialized forces also use some light tanks.