All of those ones are junk, get this one:

OCB Automatic Rolling Box - Online Shop

I have almost the same one but it is made by a company called Zen. All you do with that one is you tuck a rolling paper along the backside of the material, then you fill it up with the busted up herb, pack it down lightly, lick the glue strip, close the lid, and out pops a perfectly rolled joint.

That's the one you want. I use it and it works great. Better than any hand rolled joint I've ever smoked. :thumbsup: