I recently purchased a bumper for my white iphone 4s in Taiwan. The bumper isn't made from aluminum so there is no signal degradation and the inside is lined with silicon. What do guys think? http://www.navjack.com/product.php?KindID=2&UID=60
Checked out their web site. Nice products. They have a decent bumper case. Their metal bumper also comes in PPS, which is a plastic. First I have seen where a company made a plastic version of their metal bumper. I have had little luck with metal cases and signal loss. Let us know if you get one....
I did get the PPS versions, however, my phone is locked so its been in airplane mode. I haven't been able to see if my signal gets weaker or not, however, the box does claim that it isn't a problem.
sorry, I'm lazy, but I found a website with good photos which is my setup exactly. http://ubb.frostyplace.com/viewtopic.php?t=37438&p=205627