Features:1. PERFUSION INDEX - It includes Perfusion Index (PI%) which is an advanced feature that determines the signal quality to ensure that the user always gets accurate measurement and can make adjustments to get a better measurements. A high PI% (over 3-4%) means that you are getting a proper measurement, a low measurement means that the user needs to make adjustments to get a better reading. No more guesswork with the PO-1 Oximeter!2. ACCESSORIES - It includes a lanyard that is easy to install with an slot that easily guides the installation of the lanyard. The lanyard is great for a variety of uses such as hanging on a wall hook, belt, carabiner, and the users wrist.3. GRAPHICAL SCREEN - It i.