This product is a combination of two items, a bottle of serum and an application tool. The tool itself is a battery-powered diffuser very much like one you might use for essential oils in your workspace of home. It can be charged using a provided USB cable, and then it simply runs when the top is pulled upward. So to operate it, you pull the top upward, close your eyes, and aim the device at various parts of your face. The unit does a good job delivering a light coating of the provided serum, which you previously poured into the device (the serum provided allows for the unit to be filled twice). Close the device to shut off the diffuser.The serum provided is comfortable, pleasant, and I had no redness or irritation from its use. At this writing, 100ml refills are available for $40; the volume is about four times the amount provided in this initial package. And that brings me to the first of my two issues - the price point is quite high. The refill amount is steep, but at the refill price point, it means the diffusing device is about $60 by itself plus ten more for the initial bottle of product. Diffusers simply aren't that expensive.My second issue is whether one can use this for other products. Now I don't expect Bic to tell me if I can use Papermate refills in their pens, so I also don't expect this company to tell me if I can use other brand products in their diffuser. But this company doesn't have a long track record, and if I'm going to invest in their diffuser, I'd like to know if I can use other serums or moisturizers, or whether there's some special ingredient in their serum that makes it so that it works with the diffuser, something that other serums don't have.Three stars for the somewhat-gimmicky approach to applying expensive facial product.