I purchased the refill packs from Klingspor is 3 grits. I also purchase the Ryobi mandrels from H/D for under $6 ea. I use 180, 220, 320 grits in my hand drill. But, .....nothing takes the place of hand sanding in certain areas of a project. For an example, here is a candle holder that I make. They are in 3 sizes. Made up of a base, a bottom holder and a top holder and 8 sides pieces. I hand sand each of these pieces either by hand or on a piece of Corian tile with a full sheet of paper. Once all assembled, I use my mops to sand prior to finishing. I'm not a "high-gloss" finisher. No talent in that area but most everything gets dipped in my vat of Watco oil. After drip-drying, I wipe it all off with a rag and let it sit for about 4 days. Then maybe a light sanding with 400 paper and another dip. After a week of drying, then either a coat or two of Zinnser's spray shellac or lately I've used Johnson's paste wax for a nice warm finish.