Giant's Surelock Protector 2 LS bike lock is a solid security system for moderate crime areas.  The 13mm ultra hardened steel bar provides protection on four sides.  Combine that with a double bolt locking mechanism which is pick resistant and you get a strong piece of kit.  It will take tools and time to break through so makes a great deterrent for any thief.Weighing just over a kilogram it is not that heavy for a bike D-lock so you can easily transport it in your pack.  For those who are prone to losing keys, the Surelock Protector 2 LS comes with 4 standard keys and a very useful LED key.Weight - 1.35kg (includes keys & fittings)Features:13mm ultra hardened steel barLock: X2p double bolt locking mechanismM-Key cylinderIntegrated dust cover4 standard keys and 1 LED keyAll tube QR mounting bracket 24-40mm tubes