Isabella Awnings Circumference A-size determination

How to determine the A-circulation size of an Isabella awning?

The A-size fits perfectly into the entire rail of your caravan.
The A-measurement is the length from the ground, through the rail of the caravan to the ground (approximately 30 cm on the side). This is very easy to do using a cord (see sketch).

Each A-size corresponds to a G-size designation.
If your A-circulation size is right on the border between two different G sizes, you should choose the smaller G size to ensure that your tent fits snugly.

G10 - A675, A700, A725
G12 - A750, A775
G13 - A800, A825
G14 - A850, A875
G16 - A900, A915, A925, A940
G18 - A950, A962, A975, A989
G19 - A1000, A1015, A1025
G20 - A1050, A1075
G21 - A1100, A1125
G22 - A1150, A1175
G23 - A1200, A1225