Above is an example of a fitted hole in section. Notice that one line is used to represent two surfaces, the outside of the fastener or pin, and the inside of the hole. Fitted holes are specified according to ANSI B41-1967 (1987), in varying degrees of 'tightness', from running or sliding fits to force or shrink fits, where the pin may actually be larger than the hole. Fitted holes require a higher degree of accuracy and are typically produced by a drilling operation followed by a ream.