What is the best material for the back and side edges?
It’s a personal choice. Either Poly-With-Gauze or a double layer of lace work very well. Poly coated is a bit too thick and polyskin can tear and attaching polyskin edges to mono or lace results in a ridge at the join. If your density is 80% or over, poly-with-gauze is a very convenient edge choice. Extra light units are usually better off being all lace.
