The use of only one button enables this Bluetooth-compatible receiver to easily switch between music and phone due to the use of only one button design. The receiver has long battery life because it has built-in large-capacity rechargeable battery. And it has low power consumption and stable transmission because it adopts Bluetooth-compatible 4.2 version design. Made of metal and plastic material, it is solid and durable. The length of the product is 5cm, the width is 2cm and the height is 1cm. The product is designed to receive music from mobile phones or transmitters that feature Bluetooth-compatible wireless technology. It can be used with almost any audio receiver with an audio input jack, including automobiles. And it also supports for sound recording while charging. Item Name: Bluetooth-compatible Receiver Material: Plastic, Metal Interface Type: 3.5mm Bluetooth-compatible Version: 4.2 Battery: Built-in Battery (Included) Features: Portable, with Microphone, Hands-free Size Details: 5cm x 2cm x 1cm/1.97" x 0.79" x 0.39" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Bluetooth-compatible Receiver 1 x Metal Adapter 1 x USB Cable 1 x User Manual Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.