Model HT50P. America's best selling Hammer Tracker. How it all comes together. Roofing. Insulation. No. 1 Professional choice. An American classic. Genuine T50 Staples. Genuine T50 Staples: 5/16 inch (8 mm). No. 505; 3/8 Inch (10 mm). No. 506; 1/2 Inch (12 mm). No. 508. www.arrowfastener.com. Proudly made in the USA.