WeldingCity 5-pk Gas Diffusers 54A for Lincoln Magnum 300-400Amp and Tweco #3/#4 MIG Welding Guns Premium quality Lincoln/Tweco style MIG gas diffuser 54A Work with 14 series contact tips in Tweco #3-#4 and Lincoln Magnum 300/400 MIG guns. You get Five (5) gas diffusers 54A at this price We use U.S. Postal Service (USPS) as main carrier. Please provide a USPS deliverable address.