Those ball valves are not stainless, but plated brass.
I bought the exact same valves.
There is a thread on here that discusses these valves.
I took a file to the body, and the ball of the valve to find out for myself.
If you don't mind them being brass, but prefer the look of stainless then who cares.
The description is misleading though.
I wonder if the guy selling them knows?