I've had several plastic shakers before all of which start to develop a funky smell over time. These shakers simply don't. They're light weight but durable and also good at keeping cold liquids cooler for longer. Recommend this to anyone who has protein / other shakes on a regular basis 

The lid seal wasn't water tight so water leaked out whenever I tried to drink from it.

For the people with 1/2 star reviews saying this product leaks: please turn the lid after closing bottle. Product does not leak and keeps my cold drink cold throughout my workout.

Looks great but cap that fits in the spout snaps inside the spout.  Unfortunate really as looks really good

Really nice looking bottle, unfortunately mine leaks a little. The volume graduations are also completely useless unless you use fluid ounces. The ml graduations are 147ml then 296ml and 443ml. So pretty useless as a shaker if you frequently use fluid ounces, but considering all the suggested use of protein shakes on this site uses grams and ml, it makes things much more difficult!

Looks good, keeps your shake cold and seems to not smell unlike plastic shakers. Unfortunately it does not mix protein powder very well, no matter how hard I shake it I still get lumps. Also should be noted i'm using MyProteins Impact whey with the shaker.

Love this shaker and a massive improvement on the previous shaker - the steel design makes the shaker more durable and unique while the cap system reduces the amount of spillage from previous shaker - would highly recommend and definitely worth the expense

I have tried various types of shakers until now, and I must say that this is the most comfortable. The fit of the top piece is perfect because it has a plastic wrap on the inside, which makes it impossible for any water to spill. I also found that it is the better choice to a plastic shaker since the formation of mold is reduced and, in case that you might forget to wash it out after having a protein shake, the smell will go away at once after washing it with a bit of dish soap. It keeps drink cold or hot for a long time, especially in winter, I can make a tea and keep it warm for over two hours. I would definitely recommend it to everyone, it is really the best choice you'll make!

My favorite shaker, without a doubt. Seals very well..no leaks The agitator design in the screw cap mixes the protein powder very effectively & quickly. Durable design..loving it

Brilliant shaker, i have used many shakers. This is the absolute best i have seen. I have a habit of being rather rough with my gym bag. As a result i have broken more than a few shakers. With the full metal construction this will not be an issue for a few years. Also it doesn't hold onto that awful shaker smell the plastic ones develop after a few months (or one hot day in the back of the car)!