[StigHagen]

The pentahydrate (5 H2O) is the familiar one ("hypo") so I would get this; I'm not sure whether the 6 H2O is genuinely different or just a typo by the seller.

Edit: I see they both state they are pentahydrates, so presumably it's a typo. But I'd still be safe and get the one that is correctly identified (5 H2O).

Andrew

I have contacted the provider for details, the 6 H2O is much cheaper :-) Thank you!