The gr an it plus 640- compact and lightweight - is slightly wider than its predecessor, the future 64, and is capable of locking around reinforced parking meters despite it's compact size. It also features an array of security upgrades making this our highest security mini U-lock (12 out of 15). the 640 is made of Temper hardened steel in the shackle, case and supporting elements of the lock mechanism as well as other weight-optimized alloys. This results in a lock that is lightweight and strong. The upgraded locking mechanism now bolts four times into the lock body (two times per shackle side) providing excellent protection against twisting/torsion attacks and requiring thieves to cut both sides of the shackle in order to steal the bike while still offering great user "feel" and comfort when locking.