Roto-Flow enables equal distribution to your leaching fields. Available in 3 and 4 in sizes. The Roto-Flow gives you the low cost solution to your D-box flow regulating problems. The simple Roto-Flow for D-box outlet pipes gives you the easiest inset and forget in flow regulator available. The Roto-Flow fits both SCH 40, SDR 35 and thin wall pipe sizes. Simply place the Roto-Flow into the D-box outlet pipe and adjust to equalize flow.