VACUUM PUMP generates the necessary vacuum for the Leister VACUUM BOX and VACUUM BELL testing devices. These are used together with the VACUUM PUMP to test and ensure leak-proof, plastic weld seams.Leister’s VACUUM PUMP creates the necessary vacuum for the Leister vacuum bells BOX and BELL to test the quality of the plastic weld seams. Thus, the welding seam can be easily checked for possible leaks and weld seam errors.