Beams incorporate the strongest, most durable foam available Constructed of cross-linked Dow® Ethafoam with a top layer ofno-cut Envision™ “skin" Soft enough to crawl on but so tough we unconditionally guaranteethem for 5 years Beams are 4"L x 4"H x 51⁄2" W Includes PVC connecting rods for straight or tight angle configurations