well specifically that one is not designed that way at all, it just can be flipped - and they mark the possible angles on the stem, mtbers don't need neg rise on their stem. these however have been intentionally designed to be flipped...
I was just going on what I'd read on their website:
All Thomson Stems can be flipped and run opposite their stated rise (upside down) giving you more fit options.
I was just going on what I'd read on their website:
This