The width is not adjustable, only the height. Height is adjustable from from 3-3/4 inches to 6-3/4 inches in 1 inch increments (in product description). We can customize the width of the tray for you. Please contact us ahead of time for a custom width tray to make sure the details are entered correctly on your order. Weight capacity of our heavy duty slides is 260 pounds for both glides (in product description).