Woodcraft has five sizes of these clamps from 6" to 36". ISD3 clamps feature a unique expandable design; which allows two clamps to be combined into one single clamp. This provides the user to add an additional 6" of clamping length to their bar clamps when combined by using a quick release knob for easy changes to the expanded or reversible position. These clamps also offer a 76% increase in clamping pressure over the 500QC QuickGrip series clamps. The ISD3 still feature the "Dual Durometer" handles and are truly a "Woodworking Capable" clamp.