Knu-Vise clamps are designed to give our users the longest-lasting, most productive life possible, even in the hardest shop environments. Following is technical information common to our entire clamp lineup.The range of the toggle action clamping needs is conveniently covered by the 50, 100, 200, 400, 600, 800, 1200, 1600, 1800, and 2000 fixed mounted clamp series. These identifying clamp numerals represent the recommended clamping forces in pounds at the end of the toggle bar or jaw. The recommended clamping forces represent the forces for actual clamping; not holding force at failure of the clamp, or the maximum force. The recommended clamping forces can be increased by 15%-20% for maximum loading, or "holding force." In the case of heavy-duty clamps, the increase may be 115%-120%; i.e., the V-400 clamp has a maximum clamping force of 400+80= 480 lbs. The heavy-duty model has a maximum clamping force of 400+480=880 lbs.All parts, according to their mechanical functions, stresses, strains, and wear are scientifically heat treated. This process provides the needed mechanical properties for proper operation and longer life.