This is a CS/C mount lens ideal for looking closely at stuff. Pair it with the Raspberry Pi HQ camera to make your own circuit-inspection station or adhoc surveillance camera for your ant-colony.
It features a knurled adjustment ring to move the main lens for zoom-factor, you then focus by changing the distance to the subject. Kinda the opposite way to the human eye. Spooky!
The satin-black main barrel has a diameter of 39mm nominal for the most part, if you want to build a mount and it comes with 2 lens caps for the top and base. The whole lens is 107mm long.
We recommend plenty of supplementary light on the subject when using this lens. A simple LED torch or maybe a Unicorn HAT on full-beam will usually do the trick.