It gets the certificates of TUV,LGA and SGS. For office chairs,gas springs are used to adjust the position. 1.It has got the certificates of TUV,LGA and SGS.For office chairs ,gas springs are used to adjust the seating height.In some specialized seating products,gas sprigs are used to adjust back or seat.2.packing:20pcs/ctn gas spring(JW-A)