Pin and plug gauge sets and libraries contain multiple pin and plug gauges. Offered in Class ZZ tolerance class, these general purpose pin gauges are provided in either Go (Plus) or No-Go (Minus) gauge types, but not as mixed sets. Sets consist of dozens or hundreds of pins provided in a portable case with an insert marked with each pin's size. Libraries are stationary units or metal tool chests that contain hundreds or even up to a thousand pin and plug gauges.