We use the Rhinorack luggage bags. One has been through some very nasty storms, rain, snow, dust, etc. and kept the elements out completely and also taking some pretty good tree branch strikes. Bought two initially of the "half" bags but wish I purchased one "half" bag and one of the "small" bag, depending on the vehicle used. We only use the one and the other one just sits packed away... They have 5 different sizes to choose from.
We carry the Rhino Rack bags and I can speak to their quality as I've used one previously. They're pretty heavy duty, as is all of their equipment.
Let me know if you have any questions about them.
Thank you for letting me know. Where on your site can I find information?