This item is made of porcelain , there are no fixing points in the actual porcelain , no holes to accept the screws supplied ,you are supposed to screw against the porcelain using a rubber gromet to form a tight fit !!!!! it is without doubt the worse design for a light fitting i have ever seen , the frustration of trying to tighten two screws with rubber grometts that dont grip ( to protect the porcelain ) is absolute rubbish , because the light fitting simply falls off the screws and ends up dangling by the electric wires !!
in reality the only way to fit this item is to drill 4 holes two from above and two directly underneath the upper porcelain section and use longer screws and simply hang the light fitting like you would a picture ,
once fitted they do look very nice , but the designer needs a crisp backhand slap for the extra work and headache required to fit this item .....heres a hot tip , if you want an easy diy light this is not for you , there are better fittings on the market , if however you like a challenge you will need to use longer screws x4