This countertop support is mounted over a knee/pony wall, then into each stud on the knee/pony wall, to secure the weight of the countertop. If there is no knee/pony wall, a 2x6 must be mounted inside the cabinet and the L bracket attached spacing every 16-20 inches.Give yourself or your customer the peace of mind they deserve by having the strongest countertop support bracket on the market with the L Bracket Countertop Support.This bracket is designed to attach to a knee/pony wall or inside a cabinet.How to determine what size bracket:The bracket will be mounted over a knee/pony wall or inside cabinets. Start by measuring from the outer edge of your countertop, including the 4 inches for the knee/pony wall. For example, a 12-inch countertop overhang, plus the 4-inch knee wall gives us 16 inches. Then subtract 3 inches. This subtraction is to stay away from the outer edge of the countertop, which is usually 2-4 inches. This measurement would be 13 inches (12 + 4 -3 = 13), thus you would need to order a 13-inch L Countertop Support Bracket. Do not include the 6-inch vertical piece when determining the size to order.Dimensions of the L Bracket Countertop Support Bracket:-Length "“ [Select your chosen length when ordering bracket]-Width "“ 2 1/2 inches-Thickness "“ 1/2 inch