The lightweight TETRA LP Block dual parallel lateral underdrain system from De Nora Water Technologies offers distribution of backwash air and water for more efficient bed cleaning and reduced filter operation costs for new or retrofit applications. With no moving or wearing parts, the low-profile design is simple to install and requires minimal maintenance for long life. The GroutGrip design includes six rows of molded dovetail wedges that are embedded in the grout, offering 1.75 times the pullout strength of a conventional underdrain block. The Anchor-Rite option provides additional resistance to uplift forces by fastening the block to the filter floor with a mechanical anchor that is integral to the block. 412/788-8300; www.denora.com