Nonin Onyx II 9550 Fingertip Pulse Oximeter The Nonin Onyx II 9550 was created as an upgrade for the popular 9500. This digital fingertip pulse oximeter makes it possible for anyone to carefully monitor their blood saturation levels and pulse rate. The Onyx II Nonin 9550 offers many improvements over the original 9500 design, including approximately 800 more spot checks...Read More