It is really well built, and leak proof. Though it may seem that it is not fitting properly, it actually does and is really leak proof to a good degree. The spring can get a bit tough to clean at times, but it's not much of a hassle either. The tiny supports on the inside of the shaker which support the spring are not as sturdy as the outer construction of the bottle. Because of this, the spring can topple inside the shaker if you shake it violently. Apart from this, it is overall a great bottle for the price.