Gleaming, chromed, and very tough versions of standard Axari battle droids. Their toughness comes from the metal they are made from: Nova. These droids are bright silver, and can take massive damage. As one Galactic Defender trooper observed, one of these droids can withstand an explosion from a grenade that landed within three feet of it. It takes at least two full magazines from a standard GD projectile assault rifle to destroy, and half a magazine from a GD lazer rifle. (the lazer rifles have much more magazine capacity). As they are made of Nova, these droids are very expensive, and can only be made in limited quantaties. In addition to their toughness, they also have updated proccessors, so they are smarter than the average droid.
The GD trooper nickname for these droids is "shiners". This is obviously due to their bright, silver color.