Since I professionally every day use pulse oximeter, I naturally compare with professional equipment: This device takes about 8 seconds until it indicates the saturation. That is longer than in the professional field, but for 50 you just can not expect more. The measured values are correct when the fingers are well supplied with blood. At moderate circulation and children's fingers but falsely low values. But it should be noted that this device, I know, was calibrated by adults and not for children. Here the device is simple to its limits.
For hobby use, the device is worth the money, the emergency services do I access but would prefer to about 10 times more expensive devices.
