ARVN Paratrooper riflemen. No helmet covers.
From left to right;
MCO carrying an M16. Wearing a flack vest. 
Trooper aiming a Blooper. Wearing a locally made grenade vest.
Trooper laying down suppressive fire from behind cover. Wearing a hooded waterproof top and scarf.
Trooper reloading his M16. Wearing a scarf.