We've been getting a couple of questions about this one, so thought I'd try and address in with the FAQs!
The fixing at the headtube is made with a small plastic clip. The edges of the membrane overlap and then the fixing clips the ends together. If you scroll up to the image titled 'CAD design work' you'll see this explained in visual form.
The fixing is robust and sturdy. It's also quick to apply doesn't leave you fiddling around when fixing the unit in place. This clip also serves another purpose: when you roll the Bike Blanket up, it allows you to clip the ends of the roll together, holding it tied together when the unit's being transported when not in use.