It's the Pioneer filter by Pristine and I've never actually used it for real...only saved it for emergencies (I carry it in my EDC bag since it's barely bigger than a sharpie)

I've tested it out though and I can drain a glass of tap water fairly quickly...you don't have to suck any harder than you would for a light milkshake.

The only potential problem is that it's only good to 3 microns so it's not great against viruses or some bacteria...which is why I also have Aquatabs in the same bag.