It's a shirt number Trent Alexander-Arnold has made popular with his achievements at a tender age, but just why does the Scouser wear No.66 for Liverpool?
The answer is not that it holds personal significance; nor is it an attempt to create a unique identity within the game.
Instead, it was a result of someone carrying out a relatively common task within their job.
It turns out Lee Radcliffe, the club's kit management coordinator, is the reason why Alexander-Arnold and so many of his young admirers now bear the No.66 on the back of their Liverpool shirts.