Notes: "The K&E 620022 planimeter has adjustable length pole and tracer arms, and a tracing point rather than a magnifying glass. It is the spiritual successor to the 4242 planimeter. It has the modern closed-top design, protecting the tracing wheel and gears from dust, and incorporates a plastic wheel on the same axle as the tracing wheel, and sticking out the top of the housing. This allows the user to zero the planimeter without touching the tracing disc and getting finger oil on it."
