a gas - spring arrangement includes a gas - spring which has a substantially tubular , external casing and a rod which is guided for axial movement in the casing , between two terminal positions and is dampened by means of gas constrictions . the gas - spring includes attachment links at each end for attachment of the gas - spring between mutually movable devices or structures , such as a pivoted hood on a sunbed . the gas - spring arrangement includes a friction device which is operative to brake the relative axial movement between the gas - spring casing and the gas - spring rod , and also to fix the casing and the rod in selective relative positions , i . e ., positions between the terminal positions , and when combined with a hooded sunbed , can maintain the hood in a desired raised position .