Overload warning and protection to protect the transceiver. Package List: 1 x Power Amplifier. Usually it cost about 35USD-50USD. If you receive defective item, please kindly notify us within 14 days. This item is in the category "Consumer Electronics\Radio Communication\Ham, Amateur Radio\Ham Radio Amplifiers".The seller is "tztmotor" and is located in this country: CN. This item can be shipped worldwide.