I mainly use Bosch, Diablo and Rockler bits. Flawless, perfect fit, never disappoints. I bought them because they got great reviews. Only 3 out of 5 attachments fit on my muscle chuck. In addition, each nozzle sits differently than the others. One fell right in. Two would fit, but only with a little help. The last two didn't stand a chance. I contacted Precision Bits. They asked for photos. After I sent them in they quickly replaced the 2 bits that didn't fit and the replacement did. I realize this isn't a problem most users will have, but I think Muscle Chuck is a genius and I will never go back to routing. without it. Excellent customer service from Precision Bits. I highly recommend them.