are consumables that you need to replace on a 3m belt sander. They are good quality but still wear out with daily use, a 3m belt sander is the best I can suggest. I've found that spot welds in HSS remove much better than spot weld drills on modern cars and faster, good job 3M! Tip: Always keep a backup copy of this, your 3M belt sander will not work if it is worn out.