Fits the Standard and Demi Size '51' Vacumatic Models. These are original '51 Units Depending on where and when they were made the Plunger colour varies from Amber to Black. As with all original used parts some cleaning may be required. WHEN FITTING REPLACEMENT PUMPS MAKE SURE THE INTERNAL BARREL THREADS ARE CLEAR OF ANY DIRT OR OLD ADHESIVE. IF NOT WHEN REFITTING THE PUMP THE BARREL WILL BE STRESSED AND MAY CRACK.