Fast postage, easy to use, takes 30 seconds, for hobby purposes it seems accurate enough and to that degree, I can tell the difference between the different shades of colours. I can confirm it gives different readings for tap, reverse osmosis, fresh, salt, my home tanks and store water. Apparently the individual test are more accurate, but take a lot longer to use (i.e. 3 mins for 6 different tests). Happy with purchase (especially as it was discounted when I purchased).