2 bottles of 40ml / 1.35 fl. oz. Genuine Mercedes-Benz Windshield Washer Fluid Concentrate.
This is a windshield washer fluid concentrate and mixes with 1 gallon or 4 liters of water, preferably distilled water.
I have used this for years and it is the best I have used, and when mixed with distilled water leaves no streaks, does not have that nasty smell of premixed stuff, and cleans better than any cleaner I have ever used.
This is Summerfit and is not recommended for areas that freeze, unless you have a heated washer fluid tank.