1. Chambers was first spotted by Southampton scouts playing in a tournament in Portsmouth at the age of seven. That was in 2002 - he's just a baby!
2. The full back is a Manchester United fan. “Every young group of players our age dreams to be like the Class of ’92,” he said earlier this year. “That is everyone’s aim. Obviously, we are aspiring to be like that.”
3. His transfer fee has certainly shocked one former Gunners legend...
4. Calum is yet another star to roll off Southampton's conveyor belt of academy talent, following in the footsteps of Gareth Bale, Adam Lallana, James Ward-Prowse, Luke Shaw and new Arsenal teammates Alex Oxlade-Chamberlain and Theo Walcott.
5. He was born in Petersfield, the same Hampshire market town where George Best used to reside. If Chambers turns out to achieve half of the success that Georgie did, then Arsenal have got themselves a bargain.
6. He's already proved he can excel in the company of Arsenal's luminaries, as evidenced by his performance against the Gunners last season...
7. What's more, it seems he’s already part of the gang at The Emirates...
8. After being promoted from the Saints’ academy in 2012, he quickly made a name for himself in the club’s reserve team and was handed his England U17 debut in the same year. He featured six times for his country at that age group level, scoring three goals.
9. Chambers made his senior Southampton debut on the opening day of the 2012-13 season in the 1-0 win at West Brom, the first of only 22 Premier League appearances (including 18 starts) he made for Saints.
10. He heralds from the Nigel De Jong school of chest high tackles. Maybe he'll add some of the bite Arsenal have been lacking!
11. Eagle-eyed talent spotter Arsene Wenger undoubtedly likes him. The Frenchman said: "We are very pleased that Calum has agreed to join us. The way he adapted to the Premier League last season with Southampton at a young age shows that he has tremendous quality."
12. He is the current captain of England's U19 team - but is yet to be called up to the senior squad by Roy Hodgson.
13. He will wear number 21 as part of Arsenal's Premier League squad, replacing outgoing keeper Lukas Fabianski.
14. And the new Arsenal number 21 will make his debut for the Gunners this weekend in the Emirates Cup.
Arsenal are 1.90 to beat Benfica in the Emirates Cup on Saturday.