The lamp holder is for 2 core cable only ( no earth )
The stem on the lamp holder is an M10 1mm fine pitch and is 25mm long, this can be screwed up and down to adjust the height of your lamp holder
2 x M10 nuts and brass coupler included
Light bulbs should not touch the rim of the candle tube but have a couple of mm clearance, internally we do not recommend a tight fit.
If you are uncertain how to measure your lamp holder for your tube fitting please click this link
E27 2 part lamp holder in black and Candle Tube white Drip plastic 40mm x 85mm to fit, Smaller Dimension is the width INTERNAL dimension