This option works well having a blind over 2 panels of the window/door. Simply measure from the inside edge of the window/door frame on one side to the centre of the second window/door frame. Then from the centre of that window/door frame to the centre of the fourth window/door. Then from the centre of that window/door frame to the inside edge of the window/door frame on the other side. add 60mm to each of the outside blinds so they extend past the window frame. Enter these measurements individually into the website. For the drop measurement simply measure from the top of the window/door frame to the floor and add 40mm and select “Outside Mount”. By adding the 60mm to each outside blind this increases your chance of finding a timber stud behind the plaster. If you are fitting this way please let us know in the notes section of the ordering process. We will supply both longer screws to reach the timber and also hollow wall anchors so you can still fit your blinds even if there is no timber behind the plaster.