39", White, Dual Track Shelf Standard ,Heavy Duty Steel, Ideal For Decorative, Utility Or Filtering Applications, 1" Width, Slotted For 1-1/4" Adjustments, Stronger, Double Slotted Standards For Use With Only The 182 Series Brackets & #82 Wood Screws, 14 Gauge Steel, Can Hold Up To 450 LB Per Pair.