Patent ID: 8662166

Claim:
A centralizer comprising: an extendable collar comprising a generally tubular stop collar portion defining a bore and a generally tubular moving collar portion defining a bore that is generally aligned with the bore of the stop collar portion, the stop collar portion and the moving collar portion being slidably coupled together; wherein the stop collar portion has a first projection and a first recess and the moving collar portion has a second projection and a second recess; further wherein the first projection interfits with the second recess and the second projection interfits with the first recess; a second collar defining a bore that is generally aligned with the bore of the stop collar portion and the bore of the moving collar portion; and a plurality of ribs each comprising a first end and a second end, wherein at least some of the plurality of ribs are coupled at the first end to the moving collar portion of the extendable collar and at the second end to the second collar.