This is one of those little items that I love and is almost always within reach. I originally ordered it for my post-pole protein shakes and I now use it all day long filled with water. This simple, yet elegant, design is not only aesthetically pleasing but also easy to clean and well made. The ‘spring ‘ is genius for mixing powder/liquid and after a workout I can easily clean out the shake grits (and remove the lip gloss from the cover) quickly and easily. Better yet, the unit being glass is not only a healthier way to store and consume your liquids but keeps what is inside nice and cold.

Available from Amazon:
Sun’s Tea (TM) 21oz Borosilicate Glass Blender Bottle /Shaker Bottle with hourglass-shape Blending Spring

 
There is also a tea infuser that fits right into this unit for sale separately (Sun’s Tea Stainless Steel Deep Infuser) which works very well and is a great addition if you enjoy tea (also very easy to clean and use).