10mm hole at base
This shade carrier is ideal for mounting Tiffany and American lamp shades. The thread at the top allows you to affix the shade using the threaded finial. The stirrup at the base is designed to be fitted beneath the lampholder, meaning if you are starting from scratch you will need to wire the lampholder after fitting the stirrup.
Before starting any electrical work, always switch off at the mains. If in doubt consult a competent electrician