What is the thickness and weight (for each size)? Are they easy to cut with a shop (razor) knife?

The mats can be easily cut with a sharp razor knife. Weights are as follows: 6' x 3' weighs ~3 lbs, 6' x 5' weighs ~4 lbs, 6' x 8' weighs ~5 lbs, 6' x 17' weighs ~10 lbs, 6' x 22' weighs ~ 14 lbs