Powered flying is the luxury pushbutton alternative to manually operated raise and lower gear, for flying scenery, lighting rigs, reefer curtains, bridges and even to assist safety curtains. The principals are very similar to manual systems, except that electric hoists replace weight cradles, winches and manual effort. Most installations use individually designed pile winding or helical grooved drums, which ensure that multiple cables are hoisted evenly, thereby ensuring that the flying equipment remains level. Chain hoists are a simpler option and ideal for single and portable uses, although multi-hoist systems can become costly and configurations are more limited, whereas bespoke hoists can be made to any specification.