Rocket Launchers are what they are called. There aren't many uses for them, but they are mainly for taking down enemy helicopters and heavily armoured enemies.
The Russian RPG-7 still retains its traits in games. Point, click, ka-boom! It can be used to kill multiple enemies, or take out vehicles and Juggernaughts.
The United States/German FIM-92 Stinger shares the same name in-game. It shares all of the RPG's traits, but with one special feature: it can lock on. This makes it an air-support only weapon, and should only be even held on the levels where there are helicopters. Rios uses this weapon to kill Dalton.