My experience with them has been "so-so." I bought the "kit" that was advertised by Billy Mays on one of the TV infomercials. I only paid $15.00 for it because the seller on Ebay was in my local area. I had a "dime sized" mark that was slightly spidered. After the repair, it reduced the visibility of the crack by at least 50% - but not the full amount that I expected. For $15.00, I feel it was a worthwhile repair - just don't expect everything that is promised by the maker of the repair kit.