You must install a master unit near the start of your Gardena Micro-Drip system. A Master Unit acts to regulate the water pressure down to an effective operational pressure of 1.5 bar which will protect your fittings and keep your system running at the optimum flow rate.
The other key function of the master unit is to increase the lifespan of your set up by filtering out limescale, grit and dirt. This will prevent these unwanted particles building up in other areas of your system and causing damage.
Choose your master unit based on the size of the system. The smallest variant (Gardena Master Unit 1000) can cope with up to 1000 L per hour. If your system is larger then opt for a Gardena Master Unit 2000 which can handle up to 2000 L per hour.