“K2”?
K2 is a synthetic marijuana. I really, really doubt that’s where you were going! LOL!
What is your K2?
Menaquinone - in forms MK4 and MK7, which some nutritionists have come to believe are important in calcium metabolism:
https://en.wikipedia.org/wiki/Vitamin_K2
https://www.healthline.com/nutrition/vitamin-k2#section2