The Pen Pal 4-in-1 Makeup Pen by Alleyoop is a versatile cosmetic product that offers a highlighter, lip liner, brow pencil, and eyeliner all in one convenient pen. According to Tera's video review, this cruelty-free pen is easy to use and provides excellent results. Tera praises the lip liner, eyebrow pencil, eyeliner, and highlighter, stating that they all performed well and were her perfect shades. The twist mechanism makes it simple to access each product. Tera also highlights the convenience of this pen for touch-ups on the go. Overall, Tera highly recommends the Pen Pal 4-in-1 Makeup Pen and suggests that viewers should add it to their beauty routine.