Adored by royalty and celebrities across the globe, the a £300 smart ring has found itself centre stage at the Euros, adorning the fingers of England players and staff, who are hopeful it can give them the edge over Spain on Sunday. Bought in bulk in March by the FA – and previously described as “addictive” by defender John Stones – the hi-tech piece of titanium monitors the players’ heart rate, sleep and stress levels, calculating their readiness to train and seize victory on the pitch. Made by the Finnish health-tech startup Oura, and now in its third-generation, the ring is packed with sensors capable of continually monitoring more than 20 different biometrics, ranging from standard activity tracking to advanced heart rate variability, skin temperature, reproductive cycles and even cardiovascular age. The coaches of England will be using the data to make sure the players are getting enough quality sleep, tracking their recovery each night from training, keeping an eye on their daily stress levels and hoping it can detect any bugs they may have picked up before they can spread them to the rest of the team. The science behind it is sound. The ring records key metrics such as heart rate variability, blood oxygen levels and skin temperature each night, sending the data to a smartphone to compare it to a baseline set by the wearer over prior weeks. Any deviation from the baseline it has recorded for the wearer indicates their body is under stress, which can be caused by anything from alcohol or caffeine consumption during the day to overtraining or the flu. While the smart ring is the height of technology for most, England’s sports scientists and coaches have access to more sophisticated equipment. But the Oura undeniably has the edge in pure ease of use, as slipping on a ring is a lot easier than being hooked up to electrodes and sensors each night. Just this week Samsung launched the Galaxy Ring, and smart rings are rapidly becoming a must-have for gadget lovers and fashionistas alike. Oura rings are used by teams and sports across the world, from Spain’s Real Madrid to the NBA, Nascar and UFC in the US, plus high-profile individuals such as Lewis Hamilton, Prince Harry, Kim Kardashian and Gwyneth Paltrow. “We were really excited when the team reached out in March to purchase rings,” said the Oura chief commercial officer, Dorothy Kilroy. “It’s nice to know that we’ve potentially been a small part of their success, especially now that they’ve made their way to the final.”