Some staple sizes are used more commonly than others, depending on the application required. Some companies have unique staples just for their products. Staples from one manufacturer may or may not fit another manufacturer’s unit even if they look similar and serve the same purpose.
Staples are often described as X/Y (e.g. 24/6 or 26/6), where the first number X is the gauge of the wire (AWG), and the second number Y is the length of the shank (leg) in millimeters. Some exceptions to this rule include staple sizes like No. 10.