EZ-FIT Clear Voice Tube Compatible With Plantronics Headsets Encore,Tristar,SupraPlus,Duoset and Duopro - 2Pack 1, Compatible With H81, H91's & H101, H251's,H261's,HW251,HW261's, HW251, H171 .H141 , for Supra Plus Tristar, Encore,Duoset/Pro and Wireless CS351,CS361. 2, This Clear Voice Tube Is Not Original. 3, Easy To Install Design Quickly Replaces Worn-Out Or Dirty Head Tubes for Convenient Use. 4, 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 month. 5, Package Include 2 Pack Clear Voice Tube.