We offer this Zinc Plated bolt for the Specific purpose of mounting your Caliper Bracket to your trailers Brake Flange on the standard 4 Hole flange on 3,500lb trailer axles. You would need (4) of these bolts per flange. This bolt accommodates Kodiaks 3,500lb Caliper Mounting Brackets. This listing is for (1) Bolt and also includes (2) Galvanized Flat Washers, (1) Galvanized Lock Washer, and (1) Zinc Plated Hex Nut