This tape is used to seal the seams of the crawl space vapor barrier. It comes in 4" x 187' rolls (compare to rolls at only 108') and is white to match all of the vapor barriers we offer. This product, when installed correctly, will give you a waterproof seal at the seams. In very wet conditions it is recommended to use the Foundation Seal Tape™ under the seam to give an extra layer of protection. This tape is the perfect thickness for this application allowing proper flexibility without sacrificing strength. "Cheaper" tapes are known to release when they come in contact with moisture leaving your crawl space exposed. Just because other tapes are white does not make them the same.