multiblock seat mechanism with knee rocker functionality for office chairs, swivel chairs and other adjustable seating, also suitable for converting car seats. Replacement part for office swivel chairs and executive chairs: tiltabase plate for attaching under the seat pad to provide height adjustment and a rocker mechanism. Rocker function with locking in the zero position; hand wheel for weight adjustment with protective handle; tested safety load capacity up to 200 kg. Compatibility: suitable for all swivel chairs, office chairs and executive chairs from Topstar, Nowy Styl, Mayer, Easychair, IKEA, and other compatible brands. Use scenarios Office or home workstations: a worn chair mechanism to restore smooth tilt, height adjustment and knee rocker action on an executive or swivel chair. Multichair retrofit: upgrade multiple chairs in a workspace or home office using a consistent replacement part to extend chair life and maintain ergonomic adjustability. Vehicle seating projects: convert car seats to include adjustable height and rocker functionality for ergonomic seating in a vehicle or mobile workspace.