Selectorized strength equipment are units that have one or more weight stacks, which are rectangular weight plates that are attached to the frame and utilizes a system of pulleys. Users can choose how much weight they wish to lift by inserting a key into the desired weight stack. All the weights above the inserted key will also be lifted and are secured by two rods that run through each of the weights. Adjusting weights on a selectorized machine is extremely simple and only takes a matter of seconds. This also makes it simple to find out your maximum strength on the fly. Many selectorized strength machines are designed so you can adjust the weights without even getting up and interrupting your workout. The major drawback of selectorized equipment is the weight limit. Most weight stacks tied to the machines cannot be upgraded so if a user has reached the maximum weight on this machine and can use it without much difficulty, they will have outgrown the machine.