In short, Gruis is a mix of the leftovers of cannabis.
When cleaning the cannabis, most of the leaves and sticks are removed from the flowers (buds). Afterwards the sticks get thrown away and the leaves are saved for the Gruis. Also the powdered budremainders and buds that are too small to sell are added to the Gruis.
The more expensive varieties on the menu are often used for the ‘Strong Gruis’. The cheaper varieties on the menu are mostly used for the ‘Medium Gruis’.
Note: some people are extra sensitive to smoking sticks and leaves, and this gives them a headache. Gruis contains many leaves. If you are prone to headaches when smoking, it is better to choose a product with clean buds.