The 501 series produces 0.4 ml of fine foam per stroke from a liquid cleanser base — no propellant, no shaking. A double-mesh foam generator creates a dense, creamy lather that holds its shape, which is what facial cleanser and mousse formulas need. The 30/410 collar fits standard foam bottles; the pump is tested for consistent foam quality across 5,000 strokes and every unit passes an automatic functional test before packing.
