I've seen it, never used it. Here's what I found:
The Coralife Marine Salt Mix Solution
Dissolving 1/2 cup of Coralife Marine Salt in one gallon of purified 78°F water will yield a solution with the following properties:
Specific Gravity: 1.021-1.023
pH: 8.2 to 8.3
Calcium: 390 to 410 ppm
Magnesium: 1,110 to 1.250 ppm
*NOTE: Test results may vary with different test methods.
Take what you will from that. Seams most companies "embellish" a few of those figures too. I've used Kent a long time. Thinking about switching to Salinity, as I hear it's the best on the market (I have no clue.)