Having used the small brown disks provided with my Dremel I was not expecting much. I was so wrong. I bought these cutting wheels and a Mandrel to hold them. Within a week I was fitting a new internal door and the square steel bar that links both handles together was too long, so I set it up in my vice and to my surprise these disks cut through the bar with little effort. You have to take your time and not rush it, but it cut them cleanly and with full control. Brilliant.