i bought this bag because it was the cheapest waterproof bar bag,that i could verify fitted 31.8mm handlebars.
the fitting was a doddle (note; you will have to pinch the fittings together so the slots match up. you'll know what i mean when you try. but its no big deal)
i have now had the bag for 2 weeks and completed a 700km/450mls bike ride around Scotland in wild wet and gale/windy conditions. it has performed faultlessly and i am very impressed with the build quality.
it has enough space to carry lunch, tools, small AA road atlas, camera and a insulated top in a compression sack. has two small easy access side pockets for choccy bars.
so if you want w/proof,build quality,31.8mm/25mm fittings, then for the price this i can recommend this bag