My guess is it is very similar to xpvc. I just completed a rack out of xpvc. It's a decent product, but I still want to see how it holds up. It defiantly is not as rigid as the melamine rack I was using but is is also half the weight. What had me concerned before I build was that xpvc is actually classified as foam pvc. It is not what I would think of when thinking foam. I built an 8 high 41 qt rack. If I could do it over I would prefer two five high and stackable.