1. Built-in a high quality MP3 player with 8MB flash memory. 2. Supports inserting USB flash drive and micro-SD card as the extended storage devices. 3. Supports max. 32GB USB flash drive and max. 32GB micro-SD card. 4. 7 trigger inputs available and they can be connected with as many as 7 push buttons/switches/relays, etc. 5. Built-in a 50Wx2 class D amplifier and the audio output is powerful. Uploading audio files by connecting the micro-USB port of the device to computer with a USB data cable. Sound volume is adjustable through turning the volume knob. Able to drive an external equipment like a warning light or a motor simultaneously when it is playing a sound. Equipped with a 3.5mm audio output jack that can be connected to an external amplifier or an active speaker. Adopts solid and durable aluminium alloy case. Industrial grade design and strong anti-jamming capability. Working voltage: 12-24V DC Working current:≥8500mA 12V (when it has two 50W speakers),≥4250mA 24V (when it has two 50W speakers) Power consumption: ≤100W Flash memory size: 8MB Audio format: MP3 8 Type Trigger Modes Specification:A:Positive Trigger Ver Color: Black Material: plastic Package Contents: 1 x 7 Triggers Audio Player