Sit-to-Stand Two-Tier Base is part of Lorell Quadro Electric Adjustable-Height Workstations that accommodate different users. Once paired with a knife-edge tabletop, the complete workstation lets you alternate between sitting and standing. Dual motor allows synchronized and precise compensation for uneven loads. With smooth quiet movement, the Flex Frame base adjusts from 27-1/2" to 47" for 48" to 72" wide tabletops at a speed 1.3" per second. Base features built-in temperature and overload sensors as well as ISP (intelligent system protection) anti-collision safety feature.