Manufacturer page.

ConCore™ access floor panels are epoxy coated unitized shells. The shells consist of a flat steel top sheet welded to a formed steel bottom sheet. The panels are then filled with a highly controlled mixture of lightweight cement. Manufactured to exact toleraces, these solid panels deliver the ultimate in design, performance, plenum integrity, service, and usability. There are seven panel grades (ConCore™ 1000, ConCore™ 1250, ConCore™ 1500, ConCore™ 2000, ConCore™ 2500, ConCore™ 3000, ConCore™ 4000) and two different understructure supports to meet specific performance requirements. The two different understructures used—the Bolted Stringer and Posilock Cornerlock, which are here on out referred to as the Cornerlock and Stringer—support the floor panels for different load requirements