A telescopic module includes a first tube, a second tube, a holder, and a plurality of rollers. The first tube has a passageway. The second tube is received in the passageway of the first tube for reciprocation. The holder is mounted on the first tube. The rollers are pivoted on the holder to rest against the second tube or the first tube, or both to touch an inner side of the first tube and an outer side of the second tube to be turned when the second tube is moving.

A telescopic module, which may be incorporated in a desk or a chair to elevate or lower a work surface, includes a first tube, a second tube, a holder, and a plurality of rollers. The first tube has a passageway. The second tube is received in the passageway of the first tube for reciprocation. The holder is mounted on the first tube. The rollers are pivoted on the holder to rest against the second tube or the first tube, or both to touch an inner side of the first tube and an outer side of the second tube to be turned when the second tube is moving. The rollers may reduce the friction between the first and the second tubes when the second tube is moving.

A telescopic module includes a first tube having a passageway therein; a second tube received in the passageway of the first tube for reciprocation; a hub connected to the second tube; a roller pivoted on the hub to touch the inner side of the first tube; and an adjusting member. The hub is provided with an expanding hole and flexible portions. The roller is pivoted on the flexible portion, and the adjusting member is inserted into the expanding hole and abuts against the flexible portions to move the roller outwardly.

A telescopic module, which may be incorporated in a desk or a chair to elevate or lower a worksurface, includes a first tube, second tube, and a plurality of rollers. The first tube has a passageway, in which the second tube is received for reciprocation. The rollers are pivoted on the second tube or the first tube, or both to touch an inner side of the first tube and an outer side of the second tube to be turned when the second tube is moving. The rollers may reduce the friction between the first and the second tubes when the second tube is moving.

A telescopic module, which may be incorporated in a desk or a chair to elevate or lower a worksurface, includes a first tube, second tube, and a plurality of rollers. The first tube has a passageway, in which the second tube is received for reciprocation. The rollers are pivoted on the second tube or the first tube, or both to touch an inner side of the first tube and an outer side of the second tube to be turned when the second tube is moving. The rollers may reduce the friction between the first and the second tubes when the second tube is moving.

An automatic leg tube locking device including a hollow cylinder shaped guide switch and a circular truncated cone shaped guide post which are mutually matched for use. Through holes are evenly formed in the side surface of the guide switch, the through holes are adapted with locking shafts, a transmission mechanism is arranged between the guide switch and the guide post, so that the guide switch vertically moves along the inclined cylinder surface of the guide post and drives the locking shafts to move along the guide post when the guide switch and the guide post rotate relative to each other. A photography tripod, a unipod and a crutch are further provided. The automatic leg tube locking device, the photography tripod, the unipod and the crutch are capable of pulling the leg tube to any position and lock the leg tube automatically in a locking state.