MeasuPro Instant Read Digital Pulse Oximeter $13 at Amazon
Amazon with BetterBasics has the MeasuPro Instant Read Digital Pulse Oximeter, Pulse Rate Monitor and SpO2 Oxygen Sensor for $13 - $1 off with coupon code
OXIMTRS5 [Exp 5/31] =
$13 with free shipping on $25+ or with Prime.
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