Robotic Arm OWI-535 works and is already assembled. Arm has five controls and takes four “D” size batteries to operate. Arm comes with its original box and complete instructions to assemble, wire and operate. Arm works fine. Arm has a LED light that works located between the closing fingers at the top. Sold “as is” but you can test anything you want before you buy. I assembled this arm and it works fine!