If anyone was on the fence about trying the MA P4 props; don't be. They work as well as advertised. I have been testing them on my P4P. I estimate that they are AT LEAST 25% Quieter; which is all i wanted. I am not sure about the extended battery life that people claim. I didn't track battery data. Much quieter and I have flown them exclusively for my last 10 flights. No problems. In stock on Amazon for $19.99 US.