supply of chairs (revolving chairs) , chairs (revolving chairs): generic requirements type of chair revolving chair of adj ustable height with wheels tilt mechanism in chair centre tilt (single pivot point at seat center for simple r eclining motion) mechanism to adjust seat height hydraulic mechanism chair seat availability of cushion on seat yes seat upholstery material leatherette minimum chair seat height (in mm) 400 minimum height adjustment range of seat (in mm) 100 mm colour family of seat black chair backrest backrest height ( low-back range: 200 - 400 mm, mid-back range: 401 - 700 mm, high-back range: equal to or more than 70 1 mm) high-back backrest width (low: 400 - 550 mm, mid: 551 - 700 mm, high: equal to or greater than 7 01 mm) high locking available while tilting backrest yes colour family of backrest black lumbar support a vailable in seat backrest yes headrest available in chair no type of headrest without headrest chair arm rest armrest available in the chair no armrest type without armrest warranty minimum warranty (in yea r) 1 ]