Eureka AV20X20 20" x 20" Anti-Entrapment Stainless Steel Drain Grate are block free drain covers enhance the safety main drains and sumps in swimming pools and feature gradually sloped sides and a solid top surface. These covers prevent many objects from being drawn into the line. Most importantly; they help ensure that swimmers do not become trapped below the pool's surface by the powerful suction generated by the recirculation system.