if they are white in colour then you have just wasted your money air blocks/tablets don't work it is just another way to make money with very little benefit to the fish (in some blocks they will make your PH go throw the roof not good),
but if you are on about the air stone which connects to an air pump this can be very beneficial when it comes to exchanging gasses out of your tank for oxygen (& not a waste of money) but you will need an air pump & air hose for it to work.
hope this helps