I was recently sent Sigma's F35 brush. I was originally going to be sent the F80 but already had one which I purchased as part of the Sigmax set a few months ago, so wasn't in the need of one. Sigma very kindly offered to send me a different one instead.
I suppose it can be used for contouring but I personally think it is a little too small for it. For highlighting though, it is the perfect brush!
Atia x x x