Below is some information that customers may find helpful when placing an order or installing their lampshade.
Our medium (14") and Large (16") lampshades are both fitted with an ES fitting. 
Internal measurement of fitting: 42mm
Our Small (10") and Candle shades are fitted with Bulb Clip Fittings which simply slot on to the light bulb from above. 
Please note for the candle shade you will need a candle bulb.
For our customers based abroad particularly in the US the fitting on our shades are not the same as the fitting on your lamps. For this we recommend a simple solution of changing the original bulb holder to a E27 fitting.  This can be done easily by an electrician.  This is also the case for customers whose bulb holders are too large for the ES fitting.
Our Woven Lamp and Brass Lamp Base are wired with a UK fitting only as they are made with antique parts. Please note that if you are buying these lamp bases, they will require re-wiring, or the use of a UK to US adapter. These antique parts take a standard B22 bayonet lightbulb.
We recommend that our customers used LED lightbulbs with our shades, we think that in every way these bulbs are a better fit. They do not heat up which is great as our products are sometimes are made of natural materials that could be affected by the heat from a bulb. And more importantly, they are environmentally friendly.
All of our lampshades have their measurements listed on their individual product pages. The base measurement is in reference to the diameter of the lampshade, the slop is in reference to the height of the shade and the top is also the diameter for the top of the shade.
Base measurements: 
Candle - 5" // 12.7cm
Small - 10" // 25cm
Medium - 14" // 35.5cm
Large - 16" // 40cm