Black Bakelight with thread and without ring Lamp holder~3652 – LEDSone UK Ltd
Bulb for TGA Mobility Scooter 24v 3 W Screw Thread — discountscooters.co.uk
Edison screw - Wikipedia
Close shot of glass incandescent light bulb cap with E27 / Edison Screw 27mm thread fitting. For illuminating, UK lighting industry, lighting abstract Stock Photo - Alamy
All Threads - various lengths and widths available from Lamps and Lights
Parts List: Everything You Need to Make Your Own Pendant Lights - Snake Head Vintage
ES | E27 | Edison Screw Nickel Plain Lampholder with 20mm Base Thread