This is Knobbles and Bobbles' lovely deep red glass knob, the diameter of this knob is 3cm and the bolt will fit through a door that is up to 3cm thick. If you have different requirements, please contact us as we do have longer bolts available for some of our designs (please see the left hand menu). Each knob is supplied with the glass knob and metal fixings including bolts and washers. Any questions? Please ring us on 07746 357625.