Review on 👻 HOYOTIK Invisible Entertainment: Halloween and Christmas Edition by Noel Schmits

I use invisible ink pens in my class to learn about espionage during the American Revolutionary War. In the past I used a pen that worked perfectly and gave it to my students as gifts. This year I bought this brand, which is hardly suitable for every student. The ink is generally hard and very faint when light is held close to it. In comparison, other pens don't struggle with these two issues.