Merlin M-Pulse Lite Finger Pulse Oximeter The Merlin M-Pulse Lite fingertip pulse oximeter builds on the success of the Merlin M-Pulse to deliver a product that represents even better value for money. The M-Pulse Lite is very easy to operate oximeter featuring one-button control. Its long battery life and compact size make it an excellent choice for on-the-spot O2 and pulse rate measurements.