1.Chair Components,Gas Spring, Gas Lift 2.Model:NT-B, NT-C 3.Warranty:5years 4.Test: SGS BIFMA X5. ... 1---1.2mm, cheaper price, two year warranty(Normal)Class 2---1.5mm, cheaper price, three year warranty(Better)Class 3 ... , expensive price, five year warranty(Much Better)Class 4---2.5mm, more expensive price, five year warranty (Best)Trade TermFOB ...