Is this belt from my Dyson 07?

It's not the drive belt: That's flat, about 15mm wide and 3mm thick.

My guess is it's the seal ring that goes round the lip of the dust canister bottom lid or the sealing ring off the filter housing..

Check the parts diagrams at http://www.ukvacuumspares.co.uk/Dyson/xv07.php

John
May 2008