A bolt is made up of a bolt, nut and a sleeve. The sleeve expands when the bolt is tightened. They are similar to nail-in anchors but are capable of handling much more heavy duty usage such as podiums and stadium seating.

There are a few different types of  long coach bolts available. A definition from a mechanical engineering point of view is as follows: an expansion bolt is a bolt and nut configuration that expands when tightened into a hole.

The first is the bolt, lead sleeve and tapered nut combination. The nut is inside a lead sleeve and the whole thing is put into a hole already drilled into the material that needs to be fastened. The bolt is then fastened and the nut is pulled up towards the bolt head and this makes the lead sleeve expand and tighten in the hole.