The jacks fold down, and telescope for longer distances. These jacks are spring loaded with positive ratchet locking to hold the load without slipping - ratchet bar is *NOT* included. Can be *bolted* or *welded* to frame - DO NOT use screws as the screws will work their way loose or be pulled out. Use BOLTS if you are not wanting to weld the jacks on - *No mounting hardware is included, you will need to purchase mounting hardware at your local hardware or home improvement store.* --- **Warnings** Do not use an impact to raise or lower any of the jacks we sell as it will damage the item. Do not use the jack to lift excessive weight or tires off the ground. Jack is made to stabilize your unit, not lift unit off the ground. Vehicle frame and door jamb damage may result. Do not use these scissors jack as a tire changing jack.