The three most common transport hooks (T Hook, R Hook and Mini J Hook) are used to create this all in one cluster. The " R " hook is about the most secure way of connecting to the oblong frame holes found in most vehicles. This hook allows for a strong connection that makes it hard for the hook to release by itself. The " T " hook is known for a quick and easy connection hook. Place the hook in the oblong hole and turn it to "lock in place". This hook is only meant to be used when you are pulling perfectly straight on the frame hook hole. The last hook is the " Mini J " hook. This hook works like the " T " Hook does but it can be used when you are pulling at angles as well. This cluster also has a pear shaped ring attached to it that makes it easy to connect directly to a snap hook or a larger slip hook from a winch line or chain assembly . Many people will keep two of these clusters on their trailer for a back up or as a common attachment device All of protiedowns.com Clusters are made of grade 70 steel and zinc plated to protect it from the elements.