When using a camera slider, the two knobs on either side of the device allow you to adjust the tension in order to gain precise control over your shot. This is done by loosening or tightening these knobs which controls how far your camera moves along the rail. By adjusting the tension, you can get exactly the angle and movement that you are trying to achieve with your shot. Additionally, once your camera is attached at one end of the slider, you will be able to smoothly move it across for smooth tracking shots and even time-lapses if desired.