Extreme Max Side Mount Roller Guide On System. 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. They will fit bunk or roller-style trailers up to 3" wide x 4.25" tall. 13" rollers sit on 12 angled vertical arms. Perfect for applications where the boat is at least 3" narrower then the trailer frame. Can be adjusted up to 24" high. Great for low-profile or fishing boats. Extreme Max Guide-Ons are zinc-coated and intended for freshwater use only. Use in saltwater or brackish water will corrode and deteriorate the finish. Features of Extreme Max 3005.3825 Side Mount Roller Guide On System Includes a pair of boat trailer roller guide-ons for close applications (boat must be at least 3" narrower than trailer frame) 13" rollers mounted on 12 tube arms; Adjustable up to 24" high Zinc-coated for freshwater corrosion-resistance not intended for use in saltwater or brackish water Fits bunk or roller-style trailer frames up to 3" wide x 4.5" tall Easy bolt-on installation Package Contents: Extreme Max 3005.3825 Side Mount Roller Guide On System Extreme Max 3005.3825: Side Mount Roller Guide On System