Coopers is one of the companies that make carb drops. They are meant to be placed in bottles for bottle conditioning according to your desired carb levels. Their recommendation is 1 drop per 345-375ml bottle or 2 drops per 740-750ml bottle.
I hope you realize they are simply sugar pressed into a shape that will fit through the neck of a bottle. Most brewers I know do bulk priming. Dissolve the desired amount of sugar for a 5 gallon batch (1-5 oz corn is what I used to use) in 2 cups water. Boil, cool and pour into the bottom of the bottling bucket. Rack beer quietly over solution, stir gently with a sanitized spoon, then bottle as usual. There are many potential sources of prining sugar in addition to corn sugar. Here is a calculsator that can be used to determine the amount of priming solution based on the desired carb level. http://www.tastybrew.com/calculators/priming.html