We recently purchased a set of bearings in THE Industrial and Scientific category for our factory. Based on our own experience, we can say that these bearings are excellent in quality and build. They are perfect for high-speed applications and the dirt, grease or dust from the surroundings will not affect their performance... We appreciate the fact that these bearings are long-lasting and they can withstand heavy loads, which means less maintenance. The only downside is that they are slightly more expensive than generic bearings. Overall, we are impressed with these dustproof bearings and would recommend them to industrial users..