I should perhaps point out that not only are we on 220 volt here, but our light bulbs don’t screw into light fittings like yours probably do. Ours have a bayonet cap, about which everything you could ever wish to know is, as usual, on Wikipedia – seehere ...
A set of tubesconsistsof a number of sectionsof various lengths which are fitted together to provide the required extension.There is a back section with bayonet fitting to fit to the camera,and a front sectionwith bayonet fitting to take the lens.Thesescrewtogetherto give an extension of 10 ...