just a tip if youre thinking of shortening them....
drill the rivet straps out of both ends before you make any cuts...
the perforated tube inside will be welded at one end, and sods law will say it will be on the end you cut, meaning when you reassemble the shortened cans, it won't be long before they start rattling.
if you drill out the straps from both ends, one of the end caps will pull off attached to the tube.
dont forget when you are measuring to cut, you want the tube to push into the end cap about 1/2" on the other end, so cut the perforated tube 1/2" longer than the sleeve
oh & wrap masking tape round the sleeve to stop the blade skidding across the slippy surface & marking them!