Found this Fingertip Blood Oxigen Monitor [amazon.com]
on sale at Amazon for $14.21 with a promo code.
Coupon code MOTFUVMO
cuts 25% off, making it $14.21
Original price is $18.95
About the product
Measures quickly and accurately pulse rate and SpO2 blood oxygen saturation of arterial hemoglobin levels.
Accurately determine your SpO2 (blood oxygen saturation levels), Fast SpO2 readings, pulse measurements and display it conveniently on a large digital OLED display.
Fingertip Pulse Oximeter, Neck/Wrist Cord, User Manual, 2-AAA Batteries and 1 year warranty