The first time I saw this, I thought, now why didn't I think of that! Just when you think you're the smartest guy in the garage, someone makes you look like a dork that put snow tires on the rear of your front wheel drive Rabbit. Gone are the days of carrying flimsy plywood up into the crawl space to utilize the attic! Simply easy to install with no measuring or cutting. We even include the wood screws to secure them into place. For attics with 16" or 24" center joists. (Has there ever been a house made that doesn't have 16" joists?) Strong enough to hold 200 pounds per square! Designed to interlock with one another, and the locating tabs for the joists make this a project my 10 year old can do. Six Deck Racks 17" wide 16" long that cover 10 1/2 square feet. Three piece Deck Racks 17" wide x 24" long. Add $5.00 to normal shipping charges due to size.