Our S49 1-wire surveillance series products are lightweight, and durable. They perform in demanding situations with exceptional audio clarity. Designed in USA. This earpiece it's compatible with Vertex Standard Radio Models EVX-531 , EVX-534, EVX-539, VX-231 , VX-261. VX-351, VX-354, VX-451, VX-454 , VX-459, VX-130, VX-131,VX-160, VX-180, VX-210, VX-210A, VX-241 , VX-315, VX-400, VX-410, VX-414, VX417, VX-420, VX-426, VX-427A 1 Year Warranty.