If you need to fix a 10mm lampholder onto a bottler or vase fit one of these Rubber Bung 25-28mm and then add a lampholder with a 10mm screw entry fixing.
As you tighten up the screw on the top of the bung the rubber is compressed and grips the bottle or vase. These Rubber Lampholder Bungs have a hole through the middle to allow the flex to come up.
Fixing hole diameter 25mm to 28mm
Please note ? The internal diameter of this bung is 5.5mm so the only flex that will pass through with the insulation is 0.5mm All Braided and 0.75mm flex you cannot pass the insulated part of the flex through