This is a #30 button back with 1-1/2" long threaded nail. When anchored with a spring lock washer, the threaded nail is a fast, positive alternative to prong tufting. Just insert the nail throught the upholstered construction and fasten it on the back with a spring washer. Deep threads are designed so spring washer slides on easy, yet can’t pull off. Nail is rigidly welded to collet. This item is sold in a 1 gross box. (144 pcs. of each item.)