Palm Hybrid-Headset. Headset connectors supported: 2.5mm 4-pin. Headphone sensitivity: 94 dB, Driver type: dynamic, Acoustic system: clip-on. Compatible products: - Treo 755p - Centro - Treo 750 - Treo 700p - Treo 700w - Treo 700wx - Treo 680 - Treo 650. Compatibility: Telephone