Linear actuator for height adjustable columns comprising a threaded spindle with a longitudinal extension along a longitudinal axis, the spindle being adapted to be rotated by a driving shaft, wherein the spindle is provided with a right-hand thread at a first portion of the longitudinal extension and a left-hand thread at a second portion of the longitudinal extension, the linear actuator further comprising: a right-hand threaded nut member in threaded connection with the right-hand thread of the spindle; and a left-hand threaded nut member in threaded connection with the left-hand thread of the spindle; wherein the threaded connection of the right-hand and left-hand threaded nut member (4, 5) to the spindle provides opposite linear movement of the right-hand threaded nut member relative the left-hand threaded nut member along the longitudinal axis when the spindle is rotated. characterized in that the right-hand threaded nut member comprises a first and a second part configured to be in threaded connection with the spindle on opposing radial sides along the circumference of the spindle; wherein the left-hand threaded nut member comprises a first and a second part configured to be in threaded connection with the spindle on opposing radial sides along the circumference of the spindle;wherein, in at least a contracted state of the linear actuator, the right-hand threaded nut member and the left-hand threaded nut member extend, to a large extent, along the same portion of the longitudinal extension of the spindle; and wherein the first part and the second part of the right-hand threaded nut member have non-threaded portions (44, 45) which are at least as long as the left-hand threaded portion of the spindle in the longitudinal direction, and the first part and the second part of the left-hand threaded nut member have non-threaded portions (54, 55) which are at least as long as the right-hand threaded portion of the spindle in the longitudinal direction. a right-hand threaded nut member in threaded connection with the right-hand thread of the spindle; and a left-hand threaded nut member in threaded connection with the left-hand thread of the spindle; wherein the threaded connection of the right-hand and left-hand threaded nut member (4, 5) to the spindle provides opposite linear movement of the right-hand threaded nut member relative the left-hand threaded nut member along the longitudinal axis when the spindle is rotated. characterized in that the right-hand threaded nut member comprises a first and a second part configured to be in threaded connection with the spindle on opposing radial sides along the circumference of the spindle; wherein the left-hand threaded nut member comprises a first and a second part configured to be in threaded connection with the spindle on opposing radial sides along the circumference of the spindle;wherein, in at least a contracted state of the linear actuator, the right-hand threaded nut member and the left-hand threaded nut member extend, to a large extent, along the same portion of the longitudinal extension of the spindle; and wherein the first part and the second part of the right-hand threaded nut member have non-threaded portions (44, 45) which are at least as long as the left-hand threaded portion of the spindle in the longitudinal direction, and the first part and the second part of the left-hand threaded nut member have non-threaded portions (54, 55) which are at least as long as the right-hand threaded portion of the spindle in the longitudinal direction.