Joist brackets are made of molded plastic and attach to the deck support joists. The joist brackets support the deck ceiling and the panel combo pieces snap into the brackets. The joist brackets should be secured to the deck joists with stainless steel screws. 2-1/2" W. x 1-1/4" H. x 24-1/2" L. To figure number of parts for deck, go to www.drysnap.com and click on calculator. Use No. 8 x 1/2 zip screw model No. 703529.