These SMA to BNC female to female Adapters are nickel and gold plated with an impedance of 50 ohms. This is very popular due to a few of the Chinese import HT Radios have the SMA male pin on them and you may want to put your ext. antenna on it which has a male BNC. Also for some older cell phones, data communication, Handi-Talkies, instrumentation and video appications. This is an economical way to solve gender and connector type mismatches when interconnecting coaxial antenna equipment. Warranty: 1 year against any defect by Wiredco.