Don't waste your time.  You're not saving any money.  I took mine out of the box and before I could even connect hoses to it I noticed it wasn't even sitting flat on the bucket.  A very loose fit doesn't help either...lots of play.  With the loose fit and rocking bow I couldn't see suction pulling this tight for a better seal.  Because of the loose fit I stood there looking at it wondering how I would fasten it down to ensure any shop movement wouldn't release seal.  I quickly recognized I didn't save any money and had wasted my time.