Westone also co-developed and manufactured the early Ultimate Ears brand by Jerry Harvey, and custom-fitted in-ear musicians’ monitors.

[1] The company's earpieces are used for hearing healthcare, recreation, industrial and military applications.

Westone Audio currently has five different product families of in-ear musicians’ monitors and earphones: the Universal Series (UM Pro 10, UM Pro 20, UM Pro 30, UM Pro 50) in-ear musicians’ monitors, the W Series (W10, W10, W30, W40, W50, W60) earphones for personal listening, the custom Elite Series (ES10, ES20, ES30, ES50, ES60), the custom Consumer Recreational (CR10), custom Musician's monitors (AC10 and AC20) and custom earpieces (Style #7 and UM56) for adapting to universal-fit earbuds and earphones.

The Elite Series, namely the ES10, ES20, ES30, ES50, and ES60 are custom fit earphones and in-ear musicians’ monitors.

Custom fit is an upgrade in personal listening and in-ear musicians’ monitors.