Yeah so with that, to do 4.5asf as per caswell guide you would mix 1L of that to 3L distilled water.

You can get 1L of 98% sulphuric acid on amazon for that price, but there is an argument to be made that buying battery acid is safer. Sulphuric Acid Pure (H2SO4) Min. 98% 1*Litre https://www.amazon.co.uk/dp/B013T3EO..._Nk74zbXPCQA3M

If you go the 98% route needless to say you need to be effing careful with it, especially when mixing with water.