Compatible ONLY with Plantronics Backbeat Go 3 !! Doesn't fit Plantronics Backbeat Go 1, 1st generation earphones !! Measurements:... Small: Outer Diameter:11mm... Height:10mm .. Medium: Outer Diameter:12mm... Height:10mm .. Large: Outer Diameter:14mm... Height:10mm .. Product Description:.. -These eartips isolate sound, provide secure fit, and maximize comfort of your in ear device. -Water washable, antistatic, removable and replaceable. -Perfect fit and comfort for your ears, left and right. -Perfect replacement for any damaged, scratched or defective Earbuds Eartips. -You can also use these to provide better hygiene - when you change often. Instructions to Install Ear tips:.. -With one hand hold the ear tip and the other, the In-Ear Earphone Driver. -Place the Driver of the Earphone in the edge of the ear tip canal. -Apply pressure and with a circular motion, twist with one hand clockwise and with the other the opposite direction, until the ear tip has fully covered the Driver of the Earphone. -Once you have put them on properly, they will stay on securely