These were relatively inexpensive, were available with prime shipping, arrived on time and packaging was sufficient to protect the pulleys

I did not get a single usable pulley

but I believe good processes should result in consistent product and this is not a demonstration of that principle.

I saw another review where the product didn't appear good

Fit perfect, smooth action on bearings.

Smooth motion, diameters exactly as advertised

While at first i didn't understand why you should use this until I learn and saw how the belt would slip every so often once I replaced it work 100% with less vibration.

I bout to upgrade one my 3D printer, the dimensions are accurate and the bearings are very well made.

Perfect solution

I had the craziest popping clicking sound from my Y-axis on my Genuine Prusa MK3

These idlers are the correct size of the original Prusa

The five I received are well-made, and they arrived in good shape.

Perfectly machined

They were well packaged in double ziplock backs and were nice and clean

Eventually figured out that the Bearing in the Y-axis was bad and eventually caused failed prints

The Bearing was so bad that it feel like made out of square bearing not rounded one.

2, maybe 3 will have good bearings, the rest will be gravely or totally unusable