Currently listed as #4827. I have two of these, and at 49¢ an incredible buy. I store them with bristles nested to avoid getting poked by them. My primary use for them is cleaning files of wood and metal debris, but they're also so cheap that, as @Bigplanz and @jpoe note, they can be used for just about anything. You can get 'em really dirty and just hose them off. Shake to mostly dry, or use a compressor to blow-dry them. I have also used a heat gun when it's handy.

At 50 cents, I bought all that I could and hung them everywhere. They work great for cleaning boots off.

For 49 cents, it is the best wire brush on Earth. Why, I brushed off an inch of dried mud off my work boots just today. :)