This acoustic tube earphone is a covert listening earpiece of the type used with two-way radios, security and event-staff communication systems and discreet cueing. Sound from a small speaker in the cable body travels up a clear, coiled acoustic tube to a soft silicone ear-bud, so nothing electronic sits in the ear and the earpiece is barely visible when worn. It is fitted with a 3.5 mm plug on a 90 cm black polyurethane cable, which is Kevlar lined for strength and a long working life, and a clothing clip keeps the cable in place. The single mono speaker is 16 mm in diameter with an impedance of 110 ohms (+/-15%) and a power rating of 1.0 W normal and 1.5 W maximum. It is lightweight and comfortable for long shifts, making it popular with security guards, bouncers, hotel and venue staff, broadcast floor managers and close-protection teams. Replacement acoustic tubes and ear-buds are available separately. Check that the radio or receiver has a 3.5 mm mono earpiece socket before ordering.