This is appropriate for adding cajun spices to dishes or recipes that are already salty enough.
It's also appropriate for people who are trying to reduce their sodium intake. Tony Chachere's sells a no-salt version, but it uses a salt substitute. Not everyone likes the taste of the substitute and (ironically) some common blood-pressure medicines should not be taken along with salt substitutes.
Without the bulk of the salt, the remaining spices are stronger than in the original. Start with about 1/2 of the amount you might normally use.
(*) The 3 starred peppers have been used for roundness of flavor. They are generally available at grocery stores, but may be in a specialty mexican spice section. Any or all of them can be replaced with an equivalent amount of cayenne.