Cartier

I lunched with my brother today so I could shoot this picture which allows me to gather two Divers: the Calibre Diver by Cartier and of course the famous Submariner 14060M. It is interesting to see that the extra two mm of the Cartier make it much bigger....  

that white rubber summer strap!

I'm also interested in changing the rubber strip of my Diver for a nice alligator one, and I have a simple question: is it spring loaded or do I have to unscrew the two screws in the lugs in order to change it? Thank you in advance,

Could you provide the details on the strap? Thanks Sérgio