Structural requirements for the flip cushion should be equipped with an automatic recovery mechanism, to ensure that no load after leveling back freely. According to customer needs to set the buffer device, the seat adjuster should be adjusted freely and no locking device or limit device, the removable parts should be easy to disassemble and install, installation is convenient, the mobile requirements of the seat, should be equipped with mobile machinery, should be easy to push and pull, mobile flexible, auxiliary parts should be easy to use, moving parts should be extended.