About 3 years ago, I bought a DJ's 5" STP. What can I say? 5" is huge... created a monstrous bulge in my pants, and despite my genetics being good for that sort of thing (yes, all kids see their parents naked at some point, so don't think I'm weird), I'm 5'6", so it just looked strange. The medicine spoon receptacle is horribly uncomfortable, to the point of painful. I never did get it to work... almost 2 months of pissing all over myself incited me to give up for good. Honestly, I wouldn't recommend it. But hey, some guys seem to have made it work, so perhaps it's just me.
I'm thinking of getting one of these:
http://www.sheweeusa.com/shop/ and trying to attach it to a packer. It looks a lot less painful and invasive, so once I have the money and time to mess with all that, I may go for it.
As far as size on the packer, remember you'll probably be wearing the thing all the time. I'd go with the 3.5", unless you're 6 feet tall, which I kinda doubt (Miniar is the only lucky guy among us, as far as I know).
SD
