The x on the top of the pen is meant to stop the itching temporarily of a mosquito or insect bite. First press and apply a little pressure onto your skin and then release. Using the pen correctly should create an x on the mosquito bite. The carabiner is not my own design so I will attach the link here. The Carabiner is not needed to be used when using the bug bite pen.
The author marked this model as their own original creation.