WINBOTs are award-winning window cleaning robots equipped with patented technology, advanced cleaning systems and safety mechanisms. Uses a high-speed fan motor for strong suction, better stability and deep cleaning. W850 is one of the smallest robots of the WINBOT series, designed to fit even in small windows (18x26inches) (45x65cm). Perfectly suitable for frameless windows, uses ball sensors to detect the edges of frameless glass, cleans without the risk of falling. With the Safety Pod and Tether, cleaning high rise windows is safer than ever. Limited 1-year warranty. If customers receive a used product please contact Ecovacs customer support to receive a replacement or full refund.