w220 dash buttons

Hi All. I own a UK 2007 SLK R171 200 Kompressor and was wondering if anyone knows what the button just under and to the right of the ignition switch actually does. I've looked both online and in the owner manual and can find no mention of it anywhere. Many thanks in advance.

Hello guys Wondering if there is some one with some knowledge of w220s fuse box As there are 3 of them My problem is that I can't use any of dash board buttons as there is no light Hence can't have luxury of hazard light and central locking But not going to give up easily If...