Ergonomic Backrest Design: Featuring reliable ergonomic support, the two plastic lumbar wings support design behind the backrest which helps align the spine and reduce pressure and muscle fatigue from working. Updated Materials: Updated materials including breathable mesh and updated thick padded Seat with high density foam can provide you super comfort when sitting for a long time. Quality Assurance: All the accessories of our office chair have passed the BIFMA test, which is a guarantee for your personal safety. Multi Functions: A lever underneath the seat can adjust seat height and enable rock function. Push in to lock in place, pull out to rock. Durable Wheels Design: These 360 degree swivel mute wheels provide great mobility, suitable for hard floors, carpet, and others while being silent during swiveling and moving without scratching your floor surface. Easy to Install: Less 15 minutes for most people can be assembled, and come with all the tools necessary.