These new polypropylene plastic airless pump bottles are going to change your life! They can be used for any liquid product like serums, lotions, oils, gels, creams etc. These pumps do not use air to function, therefore your products packaged in this bottle will have a longer shelf life from not being exposed to air. The wider opening makes it so much easier to fill your viscous products so you won't need to use a funnel and then tap your product into the bottle. The natural color plastic lets your product show through so you can see as your product gets used. 1 ml of product is dispersed easily with each pump. We love these!!