Abstract: A thermoplastic resin processing machine has removably affixed onto its loading hopper a ratio loader which has a source of vacuum and two conduits leading to two different reservoirs of thermoplastic resin pellets. The ratio loader has a container having a movable internal separation wall in a vertical plane which is moved horizontally, for example, by rotation of a screwthreaded shaft having a handle at one of its ends. The ratio loader container has a bottom orifice to the thermoplastic processing machine, which orifice is coverable by a flap which is normally closed by a spring and is held closed by the vacuum.