E-32C D-ring listen only earpiece includes D-ring style earpiece and 2.5mm or 3.5mm plug connector,works with any 2.5mm or 3.5mm output such as the auxiliary port on many speaker mics. The listen only earpiece is great for adding additional privacy or for use in loud environments. Available for 2.5mm, 3.5mm, 3.5mm threaded audio jacks. Please check your radio equipment carefully to select the correct audio jack size when ordering.