I have a DF500 and was wondering if the bits would fit it. Looked up the CMT bits on Amazon. The CMT bits get very mixed reviews. 5 stars and 1 star only. Numerous people complaining the CMT bits broke and some saying the cut and chip clearing are not as good as Festool bits. Almost all of them said Festool bits last a long time and do a good job. As much as I love a bargain I think I will stick with the original.