Drippers vary in type. Each releases a certain amount of water into the pots. when timed, these drippers regulater the amaount of water your plants get allowing for a more controlled feed.
Arrow Dripper (Black Dripper)
These allow 2L/h of water to pass through them. Great for longer feeds or feeding little and often.
Flood Dripper (Blue Dripper)
These have an unrestricted flow allowing the pressure of your system to do the regulation. Ideal for heavy or aggressive feeds over a short period of time.
This dripper has a dial that the grower can adjust to regulate the flow of water. Flow ranges from 0-40L/h. Great for systems where pressure is low or feed is altered per individual plants needs.