Model YOS-550-O without desk top     The features: A. It is very smooth and quiet B. The column set up at center position  center position and off-center position. C. Movements:     Elevation Range: 685~885mm     Maximum Load: 50KG     Net Weight: 24KG     Voltage: AC 115V 60Hz, AC230V 50Hz        D. CE Certificated E. YOS-550-O is used by UL/CSA/CE safety approved elements                                                                      NOTE: Offer custom desk top size. The desk top is not included to offer with YOS Series. Must be to extra order