A chashaku is a type of tea scoop.
A Chasaku is a Japanese tool associated with Matcha tea. Matcha comes in a very fine powder form. The chashaku is a simple scoop made of bamboo. It is used to transport the tea powder from the chazutsu (tea caddy) to the chawan (bowl) in which the tea is made.
Using a chashaku makes it easier to get an idea of how much powder to use. These are used to measure the matcha powder.
The two real options you will find are the size of the tool and if the tool is "smoked" for color (susudake). The material should always be bamboo.
There are two main sizes that you will encounter: Small and Standard.
The bamboo color that we are familiar with is the typical type of chashaku but there is also a darker version of bamboo tools that is created by smoking the surface.
When this method is used it is called susudake (smoked bamboo).