Aopin Router Bit 4mm Cutting Dia 6mm Shank Dia Single Flute Straight Bit Carbide for Woodworking Milling Cutter Tool, Green, Silver, 4Pcs

The media could not be loaded.  I wanted just a bit more than 3/8 in a router bit, so I purchased this 10mm. I did note that the shaft was 6mm, but honestly thought it can't be THAT different then a 1/4? Well believe me, the difference just might make the difference in success or failure, It was the latter for me. when I dropped the bit into my router, I noticed it was more lose then normal, but was able to tighten the bit down where I certainly couldn't move it. But over 10 cuts using shallow passes this worked its way down, still spinning, and go through my work and clipped my bench. This could have been a very serious situation if it had gone further and actually released whilst spinning. Clearly meant for our friends from Europe and Canada...unless you have the proper collet for metric run away.