mine has got 5 castors, a tilt back and forward and up and down. the only thing it doesnt have yet is the bits of snot what people tend to wipe under it. Put your hand under crete and see if yours has it...
Hmmm, i just read in another post crete, preperation H will be good for your bum when you get out of your plastic chair. Apparently if you sit in a plastic chair long enough your behind will get sweaty, no matter how many castors and ups and downs it has.
Did i mention mine is black, and doesnt squeek... :)