On the backside there is two hooks to attach to your car window. The system is gravity fed do the taller the car the better flow. All is required is about two inched of clearance. Attachment is sturdy and is unlikely to fall off. Having the water system attached to the window is a benefit to me as its hard to forget about it and drive off. Also since its made of plastic even if you forget about it and drive off you'll likely hear it fall off so you can retrieve it.
The middle of the can is the cap where water is filled. I'm not sure if that's an ideal placement I would have rather seen it placed on the top to prevent possible leakage. Perhaps it was designed here to allow a larger hole and the ability for easier cleaning. The cap is sealed with a gasket so hopefully that is good enough to prevent leakage. I don't believe this is intended to be an actual shower so I'm not sure how it will fare with warmed water.
The tube is conveniently designed to be wrapped around the can. It is secured by Velcro on each side for tidy transportation and/or storage.
On the upper right hand corner is the vent. Its a simple cap that is attached by a tab to prevent loss.
The Gear Shower looks like a good system and it's manufactured here in the USA. With Kaiser out of action it might be some time before I can really test this thing out but I like what I see so far.