Planronics (15729-05) 10-Pairs Replacement Ear Foams for Headset, Earset:     H51, H51N, H61, H61N, H91, H91N, H101, H101N, SP04, SP05, PLX400, PLX500 Full Foam Ear Pads - 10 pairs They measure 2" with a 1" opening Fits most standard office style headsets Contact Headset World USA with any questions regarding compatibility