The Model 700-6X has additional links to accommodate individuals with larger upper bodies. Six links give 5 1/2 inches of distance between the cuffs. The added space reduces shoulder, arm and wrist strain for larger individuals. The Model 700-6X eliminates the need to link two sets of cuffs in order to restrain one individual. The Model 700-6X uses Model 700 Handcuffs which have been approved by the National Institute of Justice. It comes with a lifetime warranty for manufacture defects. Updated design with new lock mechanism. Two keys supplied. Made in USA.