I've tried these. I wasn't impressed. They are just thinly coated plastic sticks. The grit rubs off in no time. When I bought them I was hoping they were impregnated but found out differently. Rio Grand has some nice sanding mandrels used for jewlry making that are slotted so you can use whatever grit you want and they'll last forever. They are in all diameters and conical too. Made in Germany and are cheeper than these plastic things. I've included a link to Rio Grande.