Heavy Duty Pond Underlayment and Landscape Fabric 10x12 (120 sq ft) Heavy Duty non-Woven Geotextile Underlayment. Please Note: this listing if for fabric pond underlayment... NOT rubber pond liner! Approximately 60 ml in thickness. Increases puncture resistance of rubber/plastic liners by 400% 120 sq. feet piece (10'x12') Great for erosion control or weed control also!