Vinnfier FlipGear Tango Pro 5 WMU portable karaoke speaker as the name suggests has a built-in trolley. Now it's become easier to carry speakers outdoor by just rolling over the trolley instead of carrying it in your shoulders. With a built-in rechargeable battery, this speaker's power output is 300W. It can even play FM Radios and content from USB and Micro SD card. With dual UHF Microphone output, this can even be used in the form of karaoke.