I copied 1 previous reviewer: I fill 1 with C15 Booster (spray directly on my cheeks & decollatage). And another with Resist Daily Pore Refining Treatment 2%BHA (I spray directly into my palm, then apply with my fingers to my nose). I use very little of each product, each time. I have to refill them about one time every 7-9 days. I did have to perfect how to fill the little hole without losing any product. Luv luv luv applying these 2 products this way.