The 550000 is a much better unit, comes with adaptors to fit anything and is made out of solid brass rather than molded plastics. For the extra $20 or so (Amazon.com) than the $79 plastic unit, you have a much more flexible and long lived tool.................. It is also the same tool Porsche sells for over $500.....
We use these just about everyday in the shop, and on everything from 986/987's to motorcycles. And, no, the vacuum will not collapse the tank........