Klein Tools' 1628 Series Chicago Grips have a round inside jaw contour designed to hold weatherproof strand and solid coated wire. They also have a notched jaw to provide a firm grip on insulation. All Klein grips are manufactured from custom drop-forged steel that is machined and heat treated for excellent durability. Each grip is individually hand inspected and actuated for proper function. Grips are also rigorously tested and pulled to rated load to ensure the highest quality and reliability.