Features: Practical gift: Our battery powered doorbell can be applied as a gift, you can send it to your family member, coworker or neighbor, they may need this, very practical Household tool: You can use our wireless doorbells for home to allow you to open the door more timely for visitors and locate the door more accurately, which is a necessary tool for home. Specifications: Main material: ABS Main color: black Size: Doorbell transmitter: about 3 x 2 x 0.8 inches/ 75 x 51 x 20 mm Doorbell receiver: about 3.7 x 2.6 x 0.9 inches/ 95 x 65 x 24 mm Package includes: 4 x Wireless Doorbell Transmitter 4 x Wireless Doorbell receiver Notes: Manual measurement, please allow slight errors on size. The color may exist a slight difference due to different screen displays.