What size roller blind kit

How do I find out what size roller blind kit I need.

You need to take out either the idle end or the control end, out of the tube.

When you have got one of the ends out of your tube, you will need to

measure the external diameter of your tube. Your tube should be metal

not cardboard.

Standard sizes are 25mm, 28mm, 32mm and 40mm.

The photo below is a 25mm tube.

The photo below is a 32mm tube.

Below is the 40mm tube