I got the aluminum bumper. I think it does impact the signal. It has the same self adhesive felt inside the bumper as all the other aluminum bumpers. The fit is excellent but it will not protect the screen if dropped face first. Since they sent me the bumper late, they are gonig to send me a free tempered glass screen protector. I'm going to continue using for the next few days and see how it goes. But so far if I have the bumper on I believe I'm losing 1 bar. Any way to check exact signal strength?