These chocks wedge against and secure the corners or sides of your gear to prevent movement and rattling. Adjustable along the slats to resize and fit a variety of gear like the Wolf Pack - by Front Runner, Cub Pack - by Front Runner, Monsoon Bag - by Front Runner, Expander Camping Chair - by Front Runner, and water tanks. Secures to your rack using Eye Nuts and supplied hardware. Eye Nuts create lashing points to secure cargo using Stratchits - by Front Runner* *Note: Purchase Wolf Packs, Cub Packs, Stratchits etc. separately.