FBI Listen Only Headset for Shoulder Speaker Mic 3.5mm 1.Listen/Receive Only Covert Acoustic Tube Earpiece Headset. 2.3.5mm plug (standard headphone jack) with Acoustic Tube with metal clip. 3.Excellent for use in police, military, nightclubs, bars, paintball, security, restaurants, hotels, bouncer, warehouses and noisy environments. 4.Connection Type: Universal 3.5mm connector fits two-way radios, radio speaker mics, MP3 players and similar devices