This is a replacement caliper mounting bracket for Kodiak slip on 10 inch rotors. The bracket will only work with the slip on rotors for Kodiak brake system, and will attach to the 4 hole mounting plate on your 3,500lb axle. This is Kodiaks part number CMB-10-U-SS. This bracket is made of Stainless Steel so it will NEVER rust! The bracket will work on either the left hand or right hand side of the trailer. Kodiak offers a 6 year warranty on all of their stainless steel parts. Mounting these caliper brackets requires (4) bolts per bracket. We have these bolts available in zinc plated or stainless steel as an add on to this listing.