Each order comes with 1 Activator pen for free already, but we recommend having more available to keep your slimes the perfect texture! What is activator? Activator is what you use to spray slime if it gets too sticky. Usually your slime will arrive in perfect condition and only need activator every few weeks for upkeep, but during summer the hot climate makes it more likely that your slime may arrive melted. This is for 3 -pack of extra activator pens