Five inch sanding disks with 1/2" hole

[Mutt's37Buick]

Bought a Makita 5 inch sander (model GV5010) to grind the welds as I weld in replace metn Very light weight at 2.6 lbs. Can't seem to locate sanding disks. Looking for 24 or 36 grit disks. The sample disk has a 5" outer diameter and 1/2" inner diameter.
1) Can anyone tell me a store in the Denver area that carries this type of disk.
2) I see Aluminum Oxide, Ceramic, and Zirconia fiber disks are common. Can anyone tell me the best type of disc for grinding mild steel welds on my sheetmetal welds?
Thanks

 

[sneakysnake]

That thing seems to have a very limited amount of options on its disks.7/8s is alot more popular.
http://www.grainger.com/Grainger/MAKITA-Arbor-Mount-Sanding-Disc-5RDX2?Pid=search

 

[rainbow lungs]

Do you have a Harbor Freight by you.

They sell different ones. I like the stacked flapper disc. They come in 60 80 and 120 grit and are great for welds.

The ones at the top of this pic.

Lungs

 

[bruno]

Check out Lehigh Valley Abrasives on the web, they have everything you could possibly need.