Constant flow scuba sets do not have a demand regulator; the breathing gas flows at a constant rate, unless the diver switches it on and off by hand. They use more air than demand regulated scuba. There were attempts at designing and using these for diving and for industrial use before the Cousteau-type aqualung became commonly available circa 1950. Examples were Charles Condert dress in the US (as of 1831), "Ohgushi's Peerless Respirator" in Japan (a bite-controlled regulator, as of 1918), and Commandant le Prieur's hand-controlled regulator in France (as of 1926); see Timeline of diving technology.