12 Pcs LM8UU Linear Ball Bearings, 8mm Bore Dia, 15mm OD, 24mm Length with Double Side Rubber Seal Great for CNC, 3D Printer

Decent for the price no issues work as expected

The bearings fit very well. There will high quality and easy to use. Great product

Had a musimi bearing go bad within a month. Prusa is sending me more, but I wanted to get the printer back up and running and one of these bearings is working fantastic so far. They are cheaper than musimi, even being carefull I destroyed one by knocking out 4 balls without feeling them come out, so be very careful when packing grease and putting onto the rod. Second one went on without a hitch and is completely silent 2hrs into a 18 hour print. Works fine as a stopgap until the official ones arrive. glad to have spares too.

Not top quality but could not find better - we will see how long they last before the balls depress into the nylon housing -

These bearings are a perfect replacement for those on my MK4S. I will purchase again, if needed. Recommend you do the same.

EDIT: Perhaps I received a really, really bad batch. Been trying to get them run smoothly without success. Sorry, needed to deduct a couple of stars, it was a waste of money. They're noisy, balls fall out and don't run smooth! Not one does the job. --------------------------------------------- Yeah, not smooth. I found 3 out of 12 that are somewhat usable. To me it seems the balls aren't exactly spherically, perhaps they haven't found a way to make them round and still make a profit? I have packed them with grease coming out of their ears. Yet, there are rough spots, which is not acceptable and points to the ball. This would introduce ringing, well not really ringing. When it hits a rough spot, the stepper motor has to overcome that resistance, which may cause a slow down of the print head for example. Kinda like a vehicle that does brake in short successions. Most of us don't like that forward / backward motion, either. It would leave artifacts on the printed object. That's why 3D printer manufacturer often opt to use a aluminum extruded bar, with wheel carrier (print head or "Y" carriage) that is far less expensive than high quality linear bearings. On some, I noticed a smoother ride once I turned the bearing axial. That would actually mean the the bearing ferrule is ever so slight oval. Over time they may work better but would wear out the rod, however there is no way that they will work out of the box / bag. The ones that work smoother, have possibly a larger tolerance and don't ride on all balls. For those that can afford it, get high quality linear bearings from Misumi or other known manufacturer with high quality standards. You may get only one or two bearings at the same price tag of the 12 included in this package. The quality standard for the reviewed is rather low!

Easy replacement for my Prusa i3 Mk3.

The bearings are well built, the rubber end seals look to be nice and clean. I neglected to grease them before first use on my 3D printer, so they did start grinding after a little use. I removed, cleaned, and greased them and they work great. Very smooth and quiet action.