2PACK NSK 6203-ZZ Double Metal Seal Bearings 17X40X12MM Made in Japan Deep Groove Ball Bearings

I ordered 4 of these now, the NSK 6203-ZZ. They are sopping wet with tons of grease. The entire package is soaked in grease, before you open the plastic. They are sealed in nice plastic, and are absolutely hermetically sealed.Why am I mentioning this? Because most bearings seem to have the bare minimum of grease, and they look dry, and some of them actually feel gritty when you spin them for the first time, because the grease isn't properly circulated from the factory. These Japanese made NSK 6203 shielded bearings appear to be the only FULLY greased bearings I've come across.I've never seen any other bearings fully coated completed and squirting grease everywhere inside the packaging.Before I tried these shielded bearings, I had a horrible experience with rubber sealed new NTN bearings which squealed loudly due to the seals not having enough grease from the factory, and I had to take them off and put on these shielded bearings instead. Beware that a rubber sealed bearing with old grease, or inadequate grease, can potentially get very very hot due to the seal rubbing.If you have a machine that came with shielded bearings, it means that the machine was engineered to limit the dust and grit, either through a felt seal, or a thrust washer, or a housing, or just the air flow. Sometimes we forget about the air flow and the centrifugal force of the dust and debris. A spinning shaft cannot allow particles at the center, because particles never go to the center, they are thrown to the edges when there is a spinning cyclone of air.I've ordered a whole array of Fafnir, Timken, NTN, and the "blue rubber seal" Chinese bearings. I've always used rubber sealed bearings. However my recent experience with the brand new NTN rubber sealed bearings has made me reconsider everything. I almost overheated and ruined a 70 year old piece of equipment from the poorly greased NTN rubber sealed bearings.This led to a huge realization! If you have rubber sealed bearings, you could (in a worst case scenario) ruin your motor/machine, by overheating the side plates (if they are cast aluminum), causing loosening due to heat expansion, and finally, a spun bearing.A shielded bearing has no resistance, no heat, and doesn't even get warm, so your end cap clearances on your machinery/motor will not overheat and get loose.From now on, I'll be using these bearings, because they appear to be VERY high quality, and have TONS of grease on them.

Very good bearings

Used on 1 hp electric motor. Perfect fit and nice quality

The new bearing, same number as the old bearing, fits the shaft with lots of room to spare. It will not work with that kind of slop on the shaft!I am better off going to Ebay and buying bearings from some random guy working out of his garage.