K7 Selenium discontinued? How to upgrade to Pro?

I ran out of ink and went to purchase more. I’ve been using k7 selenium for years and from what I can tell, it is being phased out. I’ve been interested in switching to the carbon inkset for its fade resistance, but it appears the only option going forward is going to be the pro inkset? What do I need to do to switch over to Pro? Do I have to buy the whole inkset, can I mix some of my existing inks? Do I have to buy new carts for the pro inks?

K7s will continue for a while (through 2023). We are just narrowing everything to 220mL bottles (which are entirely in stock). If something shows out of stock just let me know and I’ll fix. We have 220mL bottles filled of all K7s. We ship directly from our manufacturing offices here in Vermont now.