1. The is to lengthen the phone's builtin antenna to receive messages. 2. It can prevent you from bad signal when traveling, , or taking the elevator. 3. Easy to install, simply and stick to the inner of your battery compartment. 4. Suitable for any analog, digital and triband telephone. 5. Not just for cell phones, also for enhanced signal on twoway radios, PDAs, walkie talkies, buzzers and even cordless phones in your home. Condition: Item Type: Cell Phone Signal Boosters Weight: . 20.0g Type: Signal Boosters Suitable for: Mobile phones and other smart devices color:Green Material:PCB Package Contents: 5 x Cell Phone Signal Boosters Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.