I hung two horizontally next to each other.
Turns out, they are not 100% square, and a little gap shows between them eventhough they are exactly level.
The included J formed aluminium profile to hang them is only suitable to hang them vertically.
You can hang them horizontally, means the profile looks to short, but it works.
I bought some J-mirrorhooks for $5 instead, works great.
5 stars because they are clearly advertised as Gym mirrors and I used them for residential.
Would buy again. Well packaged.