21" poly 0.060" thick. The purpose of liner protection is to protect your liner from shovel cuts, puck punctures, skate cuts, and stick hits.  THIS PRODUCT SHIPS WITH EASE via Fedex Home Delivery as it is FLEXIBLE! IT SHIPS IN COMPACT ROLLS.  It also stores easily in the offseason since it could be rolled up again at the end of the season.  Liner Protection Poly does not guarantee you an intact liner for next year but it does improve you chances to reuse your liner.   It is excellent for rinks that are built in public parks or recreation centers.   Another great benefit of 21" Liner Protection Poly for backyard ice rinks is that it is sound dampening.  When a slap shot hit the boards at night, it greatly reduces the pounding sound that can wake your neighbors.