From championship wins to his relationship with fans around the world, the caps - on sale from today - mean a lot to the seven-time world champion.
British Grand Prix 2014
Introducing the Union Jack driver's cap worn by Lewis at the 2014 British Grand Prix.
Featuring the national flag of the United Kingdom beneath the flat brim, it celebrates Lewis' first race win at Silverstone for the team.
Lewis' victory helped the team claim its first F1 Constructors' Championship that season, as the then 29-year-old went on to win his second Drivers' title.
"I always love the flag underneath," says Lewis.
"I can't remember if we were one of the first to have done that at the time, but it was always a great cap."