The Standard Cable Tie Gun is for use with 5/65'' to 3/16'' wide cable ties (2.2 mm to 4.8 mm), and the gun is made of molded nylon. The Heavy-duty Cable Tie Gun is for use with cable ties up to 1/4'' wide (6.35 mm), and the gun is made of durable metal. Tension adjustment allows the user to adapt the tool to the size of the tie