The AP3722AT with Omnidirectional -42dB 220O 57dB SMD-4P,2.2x3.8mm MEMS Microphones ROHS is a precision device manufactured by Quan Li. It is a MEMS (micro-electrical-mechanical system) microphone that is designed to offer excellent sound accuracy and reproduction. It has a -42 dB sensitivity and 220 O impedance, and uses a 4-pin SMD package that measures 2.2 x 3.8 mm. It has a high 57 dB signal-to-noise ratio, which allows it to capture audio with clarity and high accuracy. It is also RoHS compliant, meaning the product meets all EU environmental requirements.