Acoustic Release beacons are used to recover or lower equipment deployed under the sea, either in shallow or continental shelf waters. The beacon holds on to the anchor weight attached to the instrument or equipment until remotely commanded to release it. Tone burst beacons (500 Series) operate with Easytrak USBL and PAM systems. Spread Spectrum beacons (1500 Series) operate with Easytrak Nexus USBL and 3510 PAM Portable.