KOOTANS50pcs 2020 Series M3 Half Round Roll in Spring T Slot Nut for t-Slot Aluminum Profile 20x20mm

First pack 6 months ago fit fine. 2 packs bought a week ago don't fit same extrusions.I can't recommend these as something appears to have changed with the product and they won't fit my Misumi rails like the first pack did (bought those several months ago from same seller - same part number).I tried 5 from each pack and every single one was able to compress but didn't clear the extrusion when turning it to lock in place - very disappointing!

Most of them are fine but I had quite a few that were imprecise. Either too shallow and freely move around in the extrusion, or a ridge wasn't cut cleanly enough so it wouldn't fit in the extrusion straight, or too thick, or the ball spring was out and missing, etc. Still probably the best option on Amazon that I could find.

Inserting and turning to lock in place does not work for me with these and my 2020 extrusions. Other brands work fine, this brand, this product, M3 and M5 sizes did not for me.

I initially thought that these were overly saturated in oil upon arrival, but after washing it was clear that they were nearly all rusted. Some of the retaining bearings have fallen out of the nut, many are pitted.