Etymotic Research ER38-14F Foam Replacement Eartips - 10 Pack - Black Package of 10 eartips Ear canal opening 8-13mm Designed for use with ER4 series, HF series, MC series, ETY Kids, HD5-Safety, etyBLU2,ety8, HD15-High Definition Electronic Earplugs, MusicPro, Gunsport Pro, EB-15 BlastPlug, and Home Hearing Test.