... 120mm 140mm 160mm stroke SGS certificated fast shippment WSRacing Gas spring/gas lift/gas cylinder/gas strut Used for boss chair/ office chair/bar ... 100mm, 120mm, 140mm, 160mmBar Chair: 180mm, 200mm, 260mm, 330mmOuter tube color: Powder coating & Chrome Button color: White, Black, Orange, ... Class:Class is different from the thickness of medium tube & outer tube.Class D--1.2mm, cheaper price, two year ...