McMaster Carr Bubble Lifter Boot.
By DennisW

Retail rubber boot (Lifter)
McMaster Carr, part # 9744K3

It has a 1 13/16" I.D. at the top and a 3'' I.D. at the bottom. the bottom is 4 1/2.  This boot will extend to 8'' and is 2'' when collapsed. It has 9 ribs.