GSE, Cetco and Bentofix to name a few. Rolls are around 2,250 SF and 15' x 150' approx depending on the specific type. And the rolls are heavy. Basically, its bentonite clay sandwiched between 2layers of geotextile that are needle punched together. Overlap is 912 inches and you pour 1/4lb of granular bentonite clay per foot in the overlap.