1. Finger Pulse Oximeter OX300C2H- Two Waveform Displays- Six colorful and easy ways to read display options- Automatic power off - More than 30 hours of continuous operation- Uses 2 -AAA batteries or rechargeable batteries- Full 2 year limited warranty- FDA APPROVED----- 2. Finger Pulse Oximeter OX300C4P- Two displays- Automatic power off- more than 30 hours continuous operation- Full two year warranty-FDA APPROVED