While I would not call these stealth props, they are very smooth and considerably quieter than say, the Speed Blades. Running on 3s at 75 feet it is hard to hear them above normal ambient noise.
Made of a very durable polycarbonate which usually bends instead of breaking on impact. An added benefit of these blades is that when they do get bent, the bent blades can be straightened and flown a number of times before they break off.
Flies great, low noise, economical.