Flex-Drain 51510 Flexible/Expandable Landscaping Drain Pipe, Perforated with Filter Sock, 4-Inch by 25-Feet Pipe unfolds and expands from 2 to 25-feet Perforated pipe with a sock is for ground water drainage where soil is fine like sand (French drains, dispersing water from flower beds) Exceeds all applicable ASTM Standards Compatible with most traditional 3-inch and 4-inch corrugated pipe and 4-Inch PVC 30-Percent higher load-bearing rating than standard corrugated pipe