One Single Test Strip is contained to conduct ONE test of the hardness of your water ( in grains per gallon ).
Single Test includes instructions, color matching chart, and is very simple to use.
Hardness between 0 - 1000 ppm ( up to 50 grains per gallon ),

To Test:
Dip into water sample for 3 seconds.
Remove, do not shake.
Wait 20 seconds and then match with closest color block.
Colors are stable for 1 minute.