Hanna HI721-11 Iron Checker HC® colorimeter calibration standards, 0.00 and 1.00 ppm

There was a bit of a mix-up with the information on the Hanna site. This is a clear vial and a vial of something with iron in it. You have to add a packet of reagent. This worked well enough for me, but I was concerned about having to buy a new test kit every time to verify my Checker's reading. After mixing the reagent, the vial seemed to keep the color and read correctly for at least the past week. I don't know how long it will last, but it is longer than I expected, so far.