Simple to install, just push into any 4" pipe, SCH. 40, SDR 35, and thin wall. Adjustment knob moves opening up or down in 1/16" increments; total movement is 7/8". It has a watertight fit and is made with tough engineered plastic that will not corrode. By continuing, I agree to the and authorize you to charge my payment method at the prices, frequency and dates listed on this page until my order is fulfilled or I cancel, if permitted. USA Engineered and Manufactured Compare the weight. To equalize effluent flow from a distribution box. Buy Now! To be used in a septic system for even distribution of the effluent / wastewater into the leach field. Polylok Ltd, based in Athy, Co. With a focus on producing high-quality, durable components, Polylok has established itself as a global leader, supplying products that are used in. Polylok, Inc.