These bulb holders are designed to screw directly onto 20mm conduit pipe with a 1.5 pitch rise. Fitting: ES / E27 / Edison screw.
20mm Conduit Pipe Metal Lamp Light Bulb Holder Vintage Industrial | ES E27 & B22
20mm Conduit Pipe Metal Lamp Light Bulb Holder | E27 | B22 | Made in the UK
Industrial Lamp Light Bulb Holder Edison E27 Fitting Threaded 20mm Conduit Pipe
Industrial Lamp Light Bulb Holder Vintage Edison E27 Fitting 20mm Conduit Pipe
10mm Conduit Pipe Metal Lamp Light Bulb Holder Vintage Industrial | ES E27 & B22