[Daryl]

Having recently purchased a sale bulk pack of grinding discs, and the results from that, I feel it important to advise everyone about the quality control of items that are not common name brands.
Normally, the discs I purchase for my 8" Makita angle grinder were either Norton or Walter brand. These discs remove material very well, produce comparitively minimal dust, and last quite long. I happened across a bulk pack of ten grinding discs for a price that I felt may give me some cost savings (I, like everyone else, has to be vigilant for econoomy).
The first disc I installed on the grinder was severely out of balance, even though visually it displayed no runout when turned on the grinder; the same for the next four in the pack. The fifth one only lasted about thirty seconds of light grinding before it suffered a catastrophic failure. When I first felt the disc starting to go, I had just pulled my finger from the trigger and was turning it away from my body when it let go. I now have several bruises on my legs and stomach, as well as a few dents and dings in the wall and cieling of my shop. Feeling that I may have been to blame, I examined the remaining discs in the pack - the media or particulate matter displayed cracks or hazing right on the surface. I have now destroyed the remaining discs with a hammer, to prevent the being salvaged by someone else.
All this because I thought I saved 10%.
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For those of you purchasing bargain 'stuff': caveat emptor.