26mm Internal Diameter Cream Card Candle Tube
Sometimes you want a candle stick look but with a lampholder with a shade ring on the top. This will support the base of the BC switched lampholders with the internal earth, allowing the "Push bar" and shade rings to remain exposed. Sometimes these are used with smaller lampholders and restorers improvise with washers and O rings because a slightly wider tube looks better on the fitting.
Before starting any electrical work, always switch off at the mains. If in doubt consult a competent electrician