Cylinders, or similarly shaped forms, are among the most typical shapes in many models (especially aircraft, but also ships and AFVs).
Think jet and tank exhausts, ship chimneys, etc.
Many files have curved profiles, but having a perfectly semicircular sanding tool is the most convenient option by far in many cases.
This excellent tool, made of stainless steel, will allow you to achieve perfect results with virtually no effort.
We have to prepare each shipment individually as they are ordered, so allow it in 3-4 weeks to arrive in the USA/Canada (to be safe) and 3-6 weeks rest of the world, though they are usually delivered much faster.