in Gmbh & Co.Chair, in particular office chair, with a vertically adjustable back rest supportUS4844392 *18 Nov 19874 Jul 1989Fritz Bauer + Sohne OhgGas spring adjustable in length for vertically adjustable chairs, tables and the likeUS4848524 *4 Ago 198718 Jul 1989Stabilus GmbhTelescopic applianceUS4860987 *14 Jun 198529 Ago 1989Mec-Lift A.S.Adjustable telescopic devicesUS4899969 *29 Dic 198813 F