Lockwood modular extension guide Lockwood extension guide The table below shows the parts required for particular lengths Overall cylinder length required Cylinder projection Door thickness Extended base cylinder 7mm extension kit 10mm extension kit 24mm extension kit 32mm screw 42mm screw 65mm screw 41mm 43mm 49mm - 63mm 1 1 2 50mm 53mm 63mm - 83mm 1 1 1 2 61mm 63mm 83mm - 103mm 1 1 2 2 65mm 67mm 93mm - 98mm 1 1 1 2 72mm 74mm 103mm - 123mm 1 2 1 2 82mm 84mm 123mm - 143mm 1 2 2 92mm 94mm 143mm - 163mm 1 1 2 2