Here is the answer from our supplier: Unfortunately, we do not have the details of the Opel Zafira 13320946 roof rack, as it is not part of our range.

Please find enclosed the instructions for the SnowPack with all details. The screw heads are 20x20 mm in 2 different lengths as described in the instructions.

If this information is not sufficient for the customer, he can contact the manufacturer directly: https://www.thulegroup.com/en....