A distribution box is a passive flow-splitting device installed downstream of the septic tank's outlet and upstream of the leach field laterals. It receives pre-treated, settled effluent and routes it into two or more perforated lateral pipes that discharge into the soil absorption. Polylok's range of distribution boxes (a. They range from simple 4 hole distribution boxes to the large 'Rhino' 10 hole box. Accepts 12" round risers and lids. 8/4/3 (8 hole): 31”L x 17”W x 171⁄2” H Select nozzle(s) to be used. Squeeze pipe stub through cone from inside. End of cone will expand over pipe to make. The Tuf-Tite ® 7-Hole Distribution Box (Series B4) provides a permanent solution for balanced effluent flow distribution in larger septic system applications. Designed with a configuration of seven connection points and precision flow control.