The AC10-20-03 Three Rung Short Body Ladder Jack is designed for quick field adjustments. The PLATFORM CLAMP SYSTEM Clamp secures the platform to the ladder jacks and ties supporting ladders together to help secure an entire ladder jack system. The lightweight but sturdy jack mounts on either side of the extension ladder. It accepts Stages up to 20in width. Recommended for use with 300 lbs Type IA and 375 lbs Type IAA extension ladders. (OSHA and ANSI allow use with 250 lbs Type I extension ladders.)