Merkur progress

Joined
Wednesday September 26, 2012
My wifes buying me a new DE razor for xmas and I've asked for a progress.
She's had a look online and seen 3 models the 500, the 510 and the 570. Is there any difference between them apart from the choice of handle length ?
thanks
dave
 
One is longer than the other and the third is the shorter-handle version just in a posh case.