... parameters (unit:cm)HB805LABJ: Aluminum light weight chair frame, fixed armrest,flip-up footplate, solid castor, pneumatic rear ... back handle, united brake.HB863LABJ: Aluminum light weight chair frame, fixed armrest, flip up footrest, solid castor, pneumatic rear ... drop back handel, locking united brake.HB976LAB: Aluminum chair frame, fixed armrest, detachable footrest, solid castor, solid rear mag ...