I like this one:
http://www.eraser.com/catalog.cgi?mode=details&product_id=1222
The knob turns to dispense more brush as it wears down. Refills available in fine and coarse as needed, just drop in and reuse the metal holder.
http://www.eraser.com/catalog.cgi?mode=details&product_id=1222
The knob turns to dispense more brush as it wears down. Refills available in fine and coarse as needed, just drop in and reuse the metal holder.