Auto-vac desoldering tool with PH177 power head and PH178 holder requires an external vacuum source. This can be either an in-house vacuum system or air driven venturi-type vacuum source. - The DS117 is a heavy-duty unit with a large clear plastic chamber to reduce clogging, hold more debris and visually determine when maintenance and cleaning is required. Power piston in holder cleans the tip whenever Auto-Vac trigger is depressed.