There is nothing like a clean tidy sandbox to keep children of all ages safely occupied for hours and hours. The 12"" high 4" x 4" square sandbox is assemble in an hour or so, using the Frame It All joints and four feet long composite plastic timbers, which never rot, splinter and warp or lose their gorgeous natural wood grain finish. Don"t forget to also purchase the heavy duty customized sandbox cover to keep it clean and dry. 4 Stacking Joint 2-Packs. 8 Composite Plastic Timbers. 1 Square Sandbox Liner. eco-friendly made from recycled plastic. splinter and toxin free. never rots. easy to install. Sand estimated usage: 13.5 cu ft, .50 cu yards or 1400 lbs.