These are the perfect Blender Bottles! See Testimonies for the Blender Bottle: SIMPLY PERFECT! (Shelley, MD) I have always had a problem with mixing protein drinks. Either the stuff would never mix right, and/or it would somehow leak out of the blender/shaker…plus, I could never expect a lid to fit tight and stay tight while carrying the bottle somewhere. I would never have imagined how well something this SIMPLE could work so well!!!! Easy to clean, carry, and drink from too! Thanks for the reviews everyone. You all convinced me to try them, and I LOVE ”EM! Best I’ve Found (Scott, NC) “This is the first shaker bottle that works! The lid stays tight and does not leak. The wire ball mixes my shakes very thoroughly. The cap stays in place and snaps shut so you know where it is and when it is closed. The mouth to the bottle and the bottle are both large enough to handle large quantities. I might just buy another set…. ” A Kitchen Necessity (Lucy, FL) A must have in every kitchen because anything you put into them gets mixed thoroughly and they don’t leak. They’re great for my homemade salad dressings. I’ve mixed batter and puddings and everything comes out smooth. No lumps ever! Quality Supreme (Dru, AZ) Durable plastic holds up fabulously well in dishwasher and the color does not fade. The lid screws on perfectly and there are no leaks!! Mixing is so easy. This product is well engineered. All details were thought out before this product hit the market. I just can’t think of anything that needs improving! I’m sure I’ll order the smaller size . . . ! And there are lots more testimonies, too many to put here!