This top of the line "pro" quality water resistant feature-rich speaker microphone series has a built-in jack for both listen only kits and headsets. Internally upgradeable for future options such as scrambling. Side PTT next to LED illuminated function button. Speaker grill is second PTT for tactical use. Rugged quality with sealed housing for wet environments. 3.5mm threaded jack for optional headsets, throat mics and listen-only kits. Model AMPSR receiver powered by radio on most models. Model AMPSG has GPS receiver.