Adjustable column for supporting seat or stand comprises two telescopic tubes with airtight space between them, clamping screw allowing height to be adjusted and valve at bottom of column allowing air in space between tubes to be forced out

摘要

The adjustable column for supporting a seat or stand comprises two telescopic tubes (2, 3) with an airtight space between them. A clamping screw (11) allows the height of the column to be adjusted and a valve (9) at the bottom of the column allows the air in the space between the tubes to be forced out and prevents air from re-entering until the column is raised.