Fitted to none Disc Brake cycle,the extra arm certainly stops the stand from moving which has happened on other bikes I have had.
I've tried all sorts of MTB stands. This one is the best design by far. Solid even on my 29er. Highly recommended product.
Bought to use on a mountain bike riding kids in a trailer (Burley Bee). Is much more stable than I had expected and doesn't interfere with the trailer connection at all. Which I'd got it sooner!