TK-16 is a kendama brand. TK-16s have stopped being manufactured and will no longer be JKA approved, but you can still buy TKs from various websites such as Kendama USA.
The seal is green, and the kendama itself is made out of birch wood. It is said to be the most durable kendama on the market and has a very slick paint that breaks in after a long time playing with it.
According to Kendama USA pro Jake Wiens, TK-16 stands for Typical Kendama-16 centimeters.