Mono Headset with 3.5mm Connector Universal Open Speaker earbud design - Comfortable open ear fit speaker with optional use foam cushion Dynamic Speaker - Excellent Acoustic Sound for clear voice reception In-line Microphone - Conveniently located omni-directional microphone for handsfree operation In-line Call Answer/End Switch - Conveniently located multifunction button in microphone housing 3.5mm Plug - Allows direct connection into phone jack (adapter, not included, required for 2.5mm phones)