It's a Tag Heuer smart watch, designed especially for them.
https://www.tagheuer.com/en-gb/partnerships/premier-league
https://www.tagheuer.com/en-gb/news...eague-referee-app-for-the-tag-heuer-connected
Ha I wont be rushing out to spend 1200 quid on one then lolAnd all accounts, it is fairly bad. They have to wear it, but the 4th official keeps the game time.