Gray MINER'S MOSS used for Sluice Box Matting to catch fine gold and black sand. One 12' X 36' x 10mm or (3/8") for the sluice box, High Banker or dredge sluice box. The amount of black sand/fine gold I believe is 10 X's more collected then in the past using felt or indoor out door carpet. I say this as I converted my sluices to miners moss and used my sluice and high banker for 10 X's more concentrates. The price for the miners moss includes postage in the USA. $18.00 includes shipping cost.