What device is Shubman Gill wearing during India vs New Zealand 1st ODI?

Chennai India is playing New Zealand in the first of a five-match ODI series at Eden Park in Auckland on Wednesday with the next year’s World Cup in mind. During the opening few overs itself, India captain Shubman Gill was seen sporting a small, ovoid-shaped object near his eye. He was also spotted wearing it during training in the lead-up of the first match. The object is called ‘Temple’, a fitness-related device which has also been used by badminton star P. V. Sindhu in the last few months. What is Temple, the device Shubman Gill is wearing?