Unfortunately I bought from somewhere else, sort of bought impulsively in between messages with HardRacing.
Anyway, point is HardRacing's price is as good as any and I suggest you add the touch screen back pack.
I got the head strap as well, because I am also using it for board sailing.
I added another tether too, in case I get a BIG blow down and the strap gets off my head.
No point in making fish videos when I go under if the camera washes away (-:
I got the battery back pack and have a (minor) regret that for another $25 or so I could have got the touch screen back.
You can add it later, but then you have separate shipping costs.
First trials suggest the default settings give about 18 minutes of video per 4 Gig file.
I don't (yet) know why, but on the default settings it chops video up into 4 Gig chunks. (32 bit addressing ?).
I was out for about 40 minutes today and got two 4 Gig files plus about a 2 Gig one.
I can probably stitch them together easily enough, but would prefer to not have to.