The 33" set includes all that is in the 22" set, plus an additional 33" long beam block
All block bases are machined from 6061 T6 aluminum. The 33", the 22", the 11" and the 8 1/2" all feature a rounded edge on the sanding surface of the block base.
These are designed to stay straight! They won't bend, flex or warp. They use any PVA/Stik It style sand paper.
When it has to be straight, these are the blocks you "GoTo"