Amerimax FLEX-Drain 4 In. Expandable Perforated Drain Pipe With Sock Expands from 6' to 25'. Perforated FLEX-Drain with removable polyester sock can be used in most drainage applications where surrounding soil or sand is fine enough to require filtration and/or surrounding debris is considerable. The soil-tight fittings are built into the pipe and the pipe holds its shape after it is bent, therefore no other connectors need to be purchased to connect multiple pieces of drain pipe together. Simply dig your trench, lay your FLEX-Drain pipe, and cover it up. FLEX-Drain meets the Corrugated Polyethylene Pipe Association's test for crush resistance. Size 4 In. X 25 Ft., Application Drain, Outside Diameter 4.09 In., Inside Diameter 3.37 In., Length 25 Ft., Color Black, Pkg Qty 1, Package Type Sleeve