EZ-Fit Headset Voice Tube,Compatible with Plantronics SupraPlus HW251/HW261,SupraPlus H251/H261,Encore H91/H101,TriStar H81,DuoSet H141,DuoPro H151/H161/H171/H181,EncorePro HW510V/HW520V Headset Voice Tube Compatible with Plantronics SupraPlus HW251/HW261,SupraPlus H251/H261,Encore H91/H101,TriStar H81,DuoSet H141,DuoPro H151/H161/H171/H181,EncorePro HW510V/HW520V These also fit the following Plantronics Headset models:SupraPlus H251, H261, H351, H361, HW251, HW261, AH450, AH460 You should replace this vital part of your headset if the tip becomes clogged or damaged in any way. For best performance, routinely replace the voice tube every six months Packaged quantity: 1 Headset Clear Voice Tube