There used to be a small chain with a pin that locked those shut. I will ask jeff if he can remember more about that chain than I do. Like where to get it. I always thought it was just my driving. If we can find this part we will be happy to give them to anyone that purchased a refer from us. We will also post where to get them for every one else.
That would awesome, I just had mine fly open while going over a pass today, a bag of Kodachrome and a block of cheese flew out, LOL!