The shakers at Prozis have different shapes and sizes, to meet the needs of the many people who use them. Regardless of whether you're a casual gym-goer or an avid bodybuilder, you're sure to find one to your liking! Each model features a distinct ergonomic design, and a mesh strainer on the inside to prevent lump formation. All shakers are leak-proof, easy to clean, and made of high-quality BPA-free polypropylene that holds its own in the microwave, freezer or dishwasher.