1.Gas Spring,Lift,Cylinder,Strut for Chair,Table 2.Black ,chrome Surface ... spring/gas lift/gas cylinder/gas strutUse Used for boss chair/ office chair/bar chair etc.Quality ... and good service. 5 year warranty for the goods.Type Stroke for different kind of chairs. Boss chair: 60mm, 80mm Office ... , Orange, Green etc.Class Class is different from the thickness of medium tube & outer tube. Class 1---1.2mm ...