It's a BPA free item with a specially designed metal ball inside that can break up powders. It is very suitable for making protein shakes or any other beverage that needs to be added with powder. Other features include a flip-top lid, a removable bottom section, and embossed recess for easy catch.These shaker bottles have clearly marked measuring levels, so your shake tastes great and always measures up. Each one of these shaker bottles for protein mixes comes with a shaker ball, so there is no grit or lumps in your shake. Just like drinking a smoothie only your protein powder may help repair and rebuild your muscles. Logo welcome