Werner AC10-20-03 - 3 Rung Aluminum Long Body Ladder Jacks, Pair Aluminum Lightweight, sturdy, easy to use, Designed for quick field adjustments, sold as a Pair 3 Rung Model Mounts on either side of extension ladder Accepts Stages to 20 in width Recommended for use with 300 pound Type IA and 375 pound Type IAA extension ladders. (OSHA and ANSI allow use with 250 pound Type I extension ladders.) PLATFORM CLAMP SYSTEM Clamp secures platform to ladder jacks and ties supporting ladders together to help secure entire ladder jack system