[Omaroo (Chris Malikoff)]

Craig - the one closest to you adjusts the draw tension - i.e. the clamping force between the actual tube and the focus rollers. Adjust this one such that a large load (like your camera or a heavy eyepiece) doesn't slip when the unit is vertical, but the turning force you need to apply to the wheels isn't either excessive or sloppy. The focuser shoud be able to be moved to any point along its travel and when let go, the whole lot should stay put where you leave it. If the focuser slips then tighten it slowly until it doesn't.

The one furthest away from you disengages the tube from the rollers altogether - allowing to to "lock" the focus at the point you have it. Tighten this one and the wheels spin freely without moving the focuser tube.