It can attach to the bars, top tube or even a belt. I used it a ton this winter on the bars of my snow bike and even on the waistbelt of my pack.
The bag is made of waterproof material with a single adjustable QR on the front.It attaches with 2 2″ velcro straps. I was concerned it would loosen up, but not yet.
It is big enough to hold your keys, camera phone, wallet and more. I also have fit my Olympus OM-D EM5 with 24mm lens on it no problem.
Like all Baileyworks gear it is made in the USA and made to last. The quality is great and you are supporting an American manufacturing company, I have 3 other bags I use for road trips.
Baileyworks says: http://www.baileyworks.com/accessories/tt-hip-bag/options/
The TT Hip Bag features a sturdy CORDURA™ shell and Coverlight™ waterproof lining. Complete with a Packcloth interior divider and zipper pocket, one 3/4″ buckle, and two 2″ velcro straps, allowing you to carry the bag on your belt, your handle bars, or on the top tube of your bicycle. Proof that good things do come in small packages.