Sit-to-Stand Three-Tier Base is part of Lorell Quadro Electric Adjustable-Height Workstations that accommodate different users. Once paired with a knife-edge straight tabletop (sold separately, 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 24" to 50" 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.Sit-to-Stand Three-Tier Base is part of Lorell Quadro Electric Adjustable-Height Workstations that accommodate different users. Once paired with a knife-edge straight tabletop (sold separately, 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 24" to 50" 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.