It's what you pour in your dishwasher to get the glasses and dishes shiny. It lasts a few months and I couldn't find any in the grocery store. (There's a despensor in the dishwasher you just pour it in). When it's empty, the light on the front door of the the dishwasher reminds you with bright lights...which nags you to fill it.
Arrived quickly in perfect shape.
I have a Bosch dishwasher and use Cascade Platinum in.
But I think you can use other washing brands too