3030 Series M6 T Slot Nuts Roll-in Spring Ball Loaded Elastic Nuts 12 Pack Carbon Steel for 3030 Series Aluminum Extrusion Profile Rail with 8mm Slot for 3D Printer

These are not one of my recommendations. They use smaller balls than most. And are inconsistant. So very few have any resistance to movement in the 20x20 extrusions.

The M8 nuts for 3030 rails are all perfect. They have enough tension so they wont just fall through without a bolt screwed into them and tightened down, but they move easily when you try to move them. I couldn't be happier with them.BUT the M6 ones for 3030 rails were the complete opposite. Only one or two don't just fall through the rail. And to top it off, of the 12 I ordered, I received 11... As disappointed with these as I was impressed with the M8 ones

Package came sealed but completely empty. How does that happen?

The M5 variant absolutely does not fit standard 2020 slots. They're way too small and do not hold themselves in place. In my pack of 25, five actually did fit but 20 did not, so there's clearly a manufacturing defect happening here. I'm returning mine. Avoid.

Great assortment of fairly hard to find items.Fair price for a great product.Repeat business is very likely.

The ball doesn't reach the back of the profile, so they're not held in place.

These are not thick enough in standard 2020 extrusion. The ball never touches and they fall out.

These are going back. They are for 1010 rails, not 2020!