Here is one of my very favorite sticks in my collection. This is a Golding and Company adjustable Newspaper Stick. The stick is similar to regular fixed measure News Sticks - it is five inches long and is quite deep, 15 picas. However, the stick is adjustable from a 12-pica to a 15-pica measure, so a compositor could take this stick to various newspaper shops and be able to adjust the measure to whatever column-width the newspaper used. The adjustments are accomplished by loosening a screw that is in a slot on the rail and another in a slot on the body. The screw on the body is necessary because the knee does not have the long brace that most knees have that are parallel to the rail and keep the knee rigid and the measure equal along the entire depth of the stick. The second screw on the body holds the knee in place.
This type of knee, with the adjustments requiring the use of a screwdriver to loosen and tighten the screws, is the most basic form of an adjustable stick - in this case, the screw fits directly into the knee, rather than fitting into a nut of some sort that is separate from the knee itself.
This stick has a wonderful feel to it - it's a joy just holding this one in your hand, being relatively hefty for its size and with a beautiful balance. It likely dates to the mid- to late-19th Century.