3M™ Speedglas™ Sound-Dampening Breathing Tube SG-50W is a replacement sound-dampening breathing tube for 3M™ Adflo™ Powered Air Purifying Respirators when used with 3M™ Speedglas™ Welding Helmet 9100-MP, 3M™ Speedglas™ Welding Helmets 9100 FX-Air or 9100-Air. It helps to reduce noise of air source and connects the welding helmet to the turbo unit.3M Speedglas Sound-Dampening Breathing Tube SG-50W is required when used with 3M Adflo Powered Air Purifying Respirator with high-efficiency (HE) filter and organic vapor/acid gas cartridge and 3M Speedglas Welding Helmet 9100-Air, 9100MP and M-Series. Use of the tube is required at all times for the 3M Versaflo Respiratory Helmet Assembly M-405 and M-407 and the 3M Adflo Powered Air Purifying Respirator regardless of filter choice. 3M Speedglas SG-50W is not NIOSH-approved with V-Series Supplied Air Valves.