Perlite have many uses in the hydroponics and horticultural industries as a growing media. While they can be used 'as is' directly from the bag, many growers mix different ratios of the two together to make a blend that best suits their requirements. This way they get the best of both worlds - good drainage and good water holding capacity. Mixing them into cocopeat (or soil) will aid in the amount of air trapped within - improving drainage and root development.
Perlite is a heat expanded silicous rock product for use as a hydroponic growing medium. Perlite retains enough moisture for it to be effective as a hand watered medium, but also has sufficient drainage to be used in a recycling drip irrigation system. Perlite is extremely lightweight and is suitable for use in a variety of growing containers, including pots, trays, bottom fed auto watering systems, etc