Extreme Max Post Trailer Guide-Ons do more than help you get your boat on your trailer; they help stop a multitude of loading problems. They'll help you load faster and safer, keep you from loading too deep, keep your trailer position true and are especially helpful at night. Tall, easily visible, PVC-covered 40" steel posts work on bunk or roller-style trailer frames up to 3" wide x 4.25" tall. Extreme Max Post Trailer Guide-Ons are galvanized and include stainless steel hardware. 7" bolt kit available for trailer frames up to 5.25" tall (Extreme Max 3005.4050). 8" bolt kit available for trailer frames up to 6.25" tall (Extreme Max 3005.4053). 9" bolt kit available for trailer frames up to 7.5" tall (Extreme Max 3005.4056). 10" bolt kit available for trailer frames up to 8.5" tall (Extreme Max 3005.4059).