Hopkins 90124 2x4basics ShelfLinks Custom Storage System, Black - 6 Pack. Offering configurations and dimensions that other do-it-yourself shelving kits simply cannot match, the 2x4basics ShelfLinks system helps you create shelving units that suit your needs--you just add the lumber. They're constructed of heavy-gauge structural resin--once joined with 2x4s, each shelf can support spans up to 8.0 feet (2.4 meters) and can hold up to 1,000 pounds (400 kilograms). Finished shelf depth is 16 inches (40 centimeters)--plenty of room to safely house a host of items, from school books and DVD collections to tools and construction materials.