I have several lens pens with various optics manufacturers names scribed on their side. They all seem pretty functional and on par with each other.
I find them incredibly handy for my camera, binocular or riflescope lenses.
If going out in the field, I will always try to have one with me just in case.
Pros: Handy and portable for the field. Lightweight too. Cheap enough should they be lost or damaged.
Cons: I feel that these things should come in the price from the manufacturer for some of the optics you buy.
This review was written in the old system and had content requirements that are different than reviews written today.