If you have exceptionally large windows which need extra lengthy shutters, you may require a mid-rail. A mid-rail is just a way of better supporting the shutters for your window.
As a rule of thumb, if your shutters require a drop greater than 1,400mm (140cm), you will need a mid-rail. The good news is that you can choose where you would like your mid-rail to go. Our recommendation is that you match the mid-rail to any transom bars on your windows. Structurally, it is required that your mid-rail is a minimum of 380mm (38cm) and a maximum of 1300mm (130cm) from the top and bottom of your shutter.
In terms of measuring for the position of your mid-rail, measure from the bottom of your window recess to the centre of where you would like the mid-rail to sit
If you are matching the position of your mid-rail with a transom bar, measure to the centre of the bar.
Make sure the measurements are in cm and you notify of your need for a mid-rail upon ordering.