Width.( showing the top, as fitted to the car)

Recess depth

Spacer length(gauge isn't touching but trust me that's the measurement)

Over all width. Void holes are the nuisance with these IMO. See the start of the split thats more obvious from the top.

Spacer protrudes 15 mill at the top(as fitted to the car) and 15 mill from the bottom when measured from the deepest section of the flange(not including reseses or knobbly bump stop bits.)
While I'm here, some common failure points.
Part no, 90 447 156, and general corrosion and separation from the alloy spacer

What you cant see until its removed

A more common view, knobbly pushed aside reveals rust and separation, from the metal cup thats moulded into the bush itself.

This one isn't too bad compared to some I've seen. Aye Jimbob.

If your look like this, change them, before the rust eats the metal cup loosing the structural strength and they just collapse when a baring puller, or other leverage tools are applied.
Hth.