Amazon.com: KBEAR Storm IEMs 10mm Dynamic Driver Wired Earbuds Headphones with 2 Pin Detachable Cables,Noise Cancelling earbuds , Custom-Fit Earpieces (S/M/L),3.5mm Jack for Most Audio Devices(Glare,without Mic) : Electronics
Amazon.com: KZ ZSN PRO X Wired Earbuds,in-Ear Headphones with Dual Driver-Clear Sound and Ergonomic Custom-Fit Earpieces (S/M/L),Bass Ear Buds,3.5mm Jack for Phones,Computer and Laptops (Blue Without Mic) : Electronics
Westone Occupational Style 7 Custom-Fit Ear Molds for Earbuds/Jawbone and Other Brands of Earphones (One Pair) - Custom Molds for Earphones and In-Ear Devices
Custom fit earphones: Audio nirvana or a waste of money? | Ars Technica