The Brother SF-4000 Stapler Finisher option adds new paper output functions to your Brother printer including stapling, offsetting, and stacking. The SF-4000 can staple documents up to 50 pages and has an output capacity of 500 pages. The offset function shifts print jobs onto the Stapler Finisher output tray for easier collating. Staple and offset functions can be used at the same time. When the standard output tray is full, the printer will automatically place the pages onto the SF-4000 output tray, increasing the printers output capacity to 750 pages. This optional accessory includes 1,950 staples. The SR-100 replacement stapler cartridge offers a total capacity of 10,000 staples (two cartridges with 5,000 staples each