Pack of two, 28-ounce capacity (note: measurements only go to 20 ounces) shaker cups for mixing protein shakes, smoothies, and supplements Patented mixing system uses 316 surgical-grade stainless steel BlenderBall wire whisk found only in BlenderBottle brand shaker bottles Screw-on lid creates leak-proof seal, and flip cap snaps securely shut to keep contents contained; loop top for easy carrying or attaching keys Wide mouth makes it easy to add mix scoops and liquids, and embossed markings measure both ounces and milliliters Includes two shaker bottles; BPA and phthalate-free, dishwasher safe; manufacturer's limited lifetime warranty