It's a sort of sealed membrane keypad from Honeywell. Uses electrical, likely membrane or graphite-like contacts.
It seems to be the silicon cover version (rated for 1 million actuations).
More pictures of the datasheet can be found in the album.
DSC00911
DSC00912
DSC00915
DSC00919
DSC00920
DSC00921
DSC00923
DSC00886
DSC00899
DSC00880
DSC00881Flickr Album