Etymotic Research ER38-17 Glider Replacement Eartips - 3 Pairs (Discontinued by Manufacturer) Package of 6 eartips Designed for use with ER4 series, HF series, MC series, ETY Kids, HD5-Safety, etyBLU, etyBLU2, Ety-COM, HD15-High Definition Electronic Earplugs, MusicPro, Gunsport Pro, EB-15 BlastPlug, and Home Hearing Test. Ear canal opening 8-11mm. Glider style in-ear eartips