The hole saw failed at her first labor. To cut a hole circle is not possible because the centering of the drill slips on the measuring iron back and forth against the figure without existing Gewindestiftverschraubung is made. Due to this serious situation is the lack of possibility the center mount to be mounted on the measuring iron. Presumably, this was only slightly during production on the measuring iron pressed and dissolves in the first turns. This wobbles and rumbles the whole tool when introduced cutting process, which thereby is extremely dangerous. The danger of through parting tool parts to get hurt is extremely high. I recommend to the Urgent this tool not to buy and the seller of this from the range to take.
In addition, the cutter is not from higher quality steel as the picture suggests, but black and there are no spare knife for a center point as Exchange for the drill in. But that has been playing really no longer matters!