Even when using an optional speaker-microphone, the BTL amplifier output increases the audio output from the external accessory connector. The IC-F3261D series provides rugged protection against dust and water that is equivalent to IP67. The IC-F3261D series can withstand 1m depth of water for 30 minutes and its dust-tight construction shuts out powder dust, sand and other objects. The built-in GPS receiver* offers a position reporting function which sends your current position information to other IDAS radios or dispatch stations at regular intervals or preprogrammed timing. The man down function automatically sends an emergency signal when the transceiver is left in a horizontal position for a preset period. The lone worker function also can transmit an emergency signal when the radio is not operated for a preset period. These emergency functions can be used to alert your co-workers or dispatcher to any potential trouble.