I just got done using the smart power charge prop guards for an indoor live event today. Let me start off by saying that Richie over at SPC was awesome and a life saver. I guess they hit a snag with production and because I couldn't have my set in time for the event he sent his personal pair for me to use. Awesome! The prop guards are great. Light weight, stable, and most of all useful. I didn't notice any difference in flying with and without them. They take about 10 minutes to put on if you use the screws. Once on they're solid and do they're job. I ran a bump test and they worked perfectly. Those who have ordered will be happy with the product. Get at me if you have any questions.