I thought it would be interesting to take a quick look at one of these devices called the BOXYM oFit-2 from from our friends at Banggood. Once they cost hundreds of £’s. This one cost me less than £9 delivered to my door from the land of China. The unit seems to be well made and feels quite good, no flimsy plastic feel. It takes 2 AAA batteries which are not supplied. The claim of 8 hours of battery life has not been tested by me. You would realistically only be using it for seconds then it turns off when removed from your finger however it is effectively always drawing power from the batteries as there is no "hard" off switch. The menu is simple, intuitive and fairly well laid out but remember the display is not too large, ok if you are young but for the older folk among use, reading glasses may be required. Also available from Banggood! I've included quite a good description on how it works below. “The measurements are obtained by simply shining two wavelengths of light (one is a visible red beam, the other an invisible infrared beam) from LED emitters set inside the device at one side of the fingertip. By measuring how much light has passed through the fingertip and thus deducing how much been absorbed by the oxygen in the blood, an oxygen saturation or “sats” reading is established and displayed on the built-in screen as a percentage of the maximum amount of oxygen the blood could carry. The Pulse Oximeter or SATs monitor looks for minute changes in absorption as the blood is pumped past the measurement site by the beating of the heart, so selecting somewhere with strong pulse is important. A weak pulse or restricted blood flow may limit the oximeter’s ability to obtain accurate measurements. In the same way, introducing false pulses of blood, such as extreme movement of the measurement site, could equally affect the oximeter’s performance. It is important to understand what the oximeter is doing to ensure you get the best out of your SATs machine.” The above description was taken from: https://www.pulmolink.co.uk/pages/how-does-a-fingertip-pulse-oximeter-work I hope you find the video of some interest and if so please give me a thumbs up and consider subscribing. Thanks! Link to Banggood: https://www.banggood.com/custlink/mvKDMwV7sy Don't forget to give me a THUMBS UP and SUBSCRIBE. This gives me a boost to go onto making more content that I hope you will find interesting. Thanks. Hitting the notification bell will alert you to other videos new to my channel. ... https://www.youtube.com/watch?v=ZCiH7N5aQZU