
I bought this.
gosh!
Welcome to Gosh!
there is a transparent gel polymer cover, so that it lets you show the gold iphone 5s nicely.. its not a hardcase so the phone won't slip out of your hands.
some more only $25 or so at epicenter.
** oops, I noticed you asked about aluminium bumpers. so disregard
Power Support Flat Bumper Set for iPhone 5 - Power Support - BRANDS
Pros: reputable brand - expect high quality; very slim so it maintains iPhone form factor well without adding bulk
Cons: very expensive for just a bumper
Conclusion: your choice!