Type I. Tilting chair: A chair with a seat and backrest that tilt (either in unison or in synchronization)with a counterbalancing force.Chairs of this type are typically referred to as synchro-tilt,center-tilt,knee-tilt,etc.
Type II. Fixed seat angle,tilting backrest:
A chair that provides a fixed seat angle with a tilting backrest.
Type III. Fixed seat angle,Fixed backrest:
A chair that provides a fixed seat angle with a fixed backrest.This may include chairs with legs,including sled base chairs.