The WMM7027ATHD1-4/TR with SMD-4P,1.9x2.8mm MEMS Microphones ROHS is a microphone manufactured by Will Semiconductor. It is a surface mount device designed to be mounted on a printed circuit board, and is an extremely small device measuring 1.9x2.8mm. It is capable of high-quality audio recording, using a MEMS (Micro-Electro-Mechanical System) acoustic sensor. It is also RoHS compliant, meaning that the device contains safe, low-toxicity materials.