Helmetor® has been designed to hold your helmet securely.
A single vent between 30 - 65mm is all that is required.
With the supplied screws attach it to an appropriate flat surface. To use, simply put the 'foot' of the Helmetor through the vent first, then just lift the helmet up and over the top 'arm'. Both the 'foot' and 'arm' should be in the same vent.