The Protei-5 (Протей-5) is a small Russian one-man diver propulsion vehicle often used by Russian commando frogmen. It is battery electric powered, using six non-sealed lead–acid batteries. It clips on under the diver with a clip over each shoulder and one up between his legs. Its casing is aluminium. It was intended to be clipped onto the outside of a submarine; near the operation site the frogmen would airlock out underwater and unhitch their Protei 5's and ride them to the operation site. It seems to have been intended to be ridden fast and far rather than for complicated maneuvering.