These heavy-duty staples are designed for safe and secure installation of NM (Romex®) cable gauges 14/3, 14/3G, and 12/3, and other wire up to 19/32-Inch (15 mm) in width. For exclusive use with Klein's Loose Cable Staplers (Cat. Nos. 450-01 and 450-100). These UL listed insulated staples are available in packs of 300.