Check the listing for details. Garrett 1/4" Headphone Adapter for Garrett AT Pro, Infinium & Sea Hunter Models. Condition: New. Listed at 33.95 USD. Garrett 1/4" Headphone Adapter for Garrett AT Pro, Infinium & Sea Hunter Models Allows land-use headphones with a 1/4” male jack to be used with the Garrett ATX, AT Gold, AT Pro, AT Pro International and Sea Hunter models. (Not intended for submerged use.) OPERATION NOTES: Inserting the headphone plug into the connector will provide sound from the headphones only and will automatically disable the detector’s speaker. This automatic speaker-disable feature requires the input impedance of the headphones to be 10,000 ohms or less. Note that some non-Garrett headphones may not meet this requirement and will require the addition of a 10,000 ohm termination resistor inside the connector to disable the speaker.Garrett 1/4" Headphone Adapter for Garrett AT Pro, Infinium & Sea Hunter Models Allows land-use headphones with a 1/4” male jack to be used with the Garrett ATX, AT Gold, AT Pro, AT Pro International and Sea Hunter models. (Not intended for submerged use.) OPERATION NOTES: Inserting the headphone plug into the connector will provide sound from the headphones only and will automatically disable the detector’s speaker. This automatic speaker-disable feature requires the input impedance of the headphones to be 10,000 ohms or less. Note that some non-Garrett headphones may not meet this requirement and will require the addition of a 10,000 ohm termination resistor inside the connector to disable the speaker.