Heavy-duty stapler takes 40 percent less effort to staple up to 140 sheets of 20 lb. paper. Stapler uses various sizes to fasten a certain number of sheets. 1/4" staples secure up to 30 sheets. 5/16" staples fasten from 31 to 50 sheets, 3/8" staplesfrom 51 to 70, 1/2" staples from 71 to 100, 9/16" from 101 to 120, and 5/8" staples secure from 121 to 140 sheets. Design also features patented jam-free design, adjustable throat depth (3/16" to 2-3/4"), and front-loading, full-strip channel.