The medium-sized, left-ear C806573-LM from Otto Engineering is a flexible open-ear insert made of hypo-allergenic plastic and designed to fit securely over the acoustic tube elbow of surveillance kits (professional models) such as the One Wire Earphone kit, the Two Wire Palm Microphone kit, and the Three Wire Mini-Lapel Mic kit. It is well suited for users who are sharing equipment in multiple-shift operations or users wearing ear inserts for extended periods of time.