flow - rate limiting device in a single - control mixer cartridge for hot and cold water including a body associated with a bottom for containing a fixed plate and a movable plate coupled with an actuation lever pivoted on a rotating coupling ; the flow - rate limiting device includes a bush suitable to be associated with the lever and having a plurality of protrusions of different thicknesses which are adapted to selectively constitute an element for contrast against the stroke limiter of the lever which corresponds to the maximum flow - rate position .