Factory 'stock' replacement foam eartips for the ER4S, ER4P/PT, HF2/3/5 and MC2/3/5 earphones. The Etymotic ER-4 series (ER-4B, ER-4P, and ER-4S) come with two different eartips: black foam and white rubber. The foam eartips are comfortable but like all great things, they too must pass in time. For whatever reason—wear, tear, or just plain 'I forgot where I put them'—you'll eventually need some replacements. They come in a package of 10 (5 pairs). NOTE: Eartips are NOT returnable due to hygiene/health concerns.