i am using an iPhone casing which has antenna enhancer, i bought this from an apple reseller shop. Its not an apple product, but the quality and the material used is kinda the same with apple original casing. The name in the box is Active Case S+
it really works! before,,im having problem with poor signal so when i saw this case, i bought it right away!
by the way i bought the product in Senco shop in Tomas Morato Quezon City.