I purchased these 12” mounts to replace 6” units that were not long enough for my new boat. I mounted them on a EZ loader trailer. I cannibalized the uprights and load guides from my previous boats Pacific trailer. I did have the old uprights extended 5” so the guide board would center on the rub rail and another rung added to the ladder with the rung spacing adjusted to even them out. The new mounts and guide bunks with built in ladder from the Pacific Trailer are a great addition to my new trailer and boat.