A smart ring measures pulse and skin temperature, counts steps and determines sleep quality, among other things. In this respect, it is similar to a smartwatch. But it is smaller, lighter - and less conspicuous. After all, not everyone likes to wear an occasionally vibrating mini screen on their wrist, preferring a conventional wristwatch - if they wear one at all...

The Helio ring is one of the cheapest rings on the market that still offers a good deal. Unfortunately, it is only available in three sizes. However, it provided accurate heart rate measurement and quite good sleep analysis when tested. The battery life of two days could be improved. The charging process is also not possible without a power cable.