Yes pretty much a demand regulator... they did away with the needle & seat and the lifting arm with the spring underneath... those button disc valves do the same thing... if you look at the atmosphere metering diaphram just behind the back cover plate, draw from the venturi moves the metering diaphram against the button disc valve which opens the valve to let fuel into the metering chamber, works similar to walbros... I like the walbros because they're easily serviced... but saitos idea has less moving parts to wear, no metering arm height adjustment, etc... but it's just an r&r replacement part as a whole... as you found, it's hard to locate that part# 160, which is the fuel pump / regulator section... that consist of all the soft parts, diaphrams, button valves, etc, as well as the hard parts, intermediate and back cover plates... they don't sell just the soft parts alone.