In general, it is wise to invest in something that you will use frequently. There are some problems, but they aren't major.
POLAR H10 HR Sensor: Bluetooth Enabled, 🏋️ Black, M-XXL – Advanced Accuracy for Heart Rate Monitoring
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Smart bracelet Xiaomi Mi Smart Band 5 Global, black
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Track Your Oxygen Levels And Heart Rate With IProven Fingertip Pulse Oximeter – Includes Battery, Case, And Lanyard In Blue
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Accurate No-Touch Thermometer For Adults And Kids With Fever Alert And Memory Recall
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