The GHL Doser 2.2 has an updated (faster and easier to setup) WiFi Chip compared to the 2.1 version.
The GHL Doser 2.2 is available as a Stand Alone Unit (SA), as well as an Extension Unit (EXT).
The GHL Doser 2.2 Stand Alone has integrated control electronics and works on its own. 
It includes two PAB-ports for connecting additional GHL Doser 2.2 EXT, Maxi Doser EXT, or KH Director devices via ProfiLux Aquatic Bus.
PAB is an interference-free CAN-Bus-System that allows for extremely secure data transfer between all PAB devices such as additional GHL Doser 2.2, KH Director, and GHL Doser Maxi Slave devices. The range can be up to 100 m (300 FT).
PAB cables are not included and must be purchased.
One GHL Doser 2.2 SA is able to control 3 additional GHL Extension Dosers (GHL Doser 2.2 EXT or GHL Doser Maxi 2.1/ 2.2 EXT) and can thus be extended to a dosing system with a total of 16 pumps.
The device is comfortably operated from your smartphone or your PC. The connection is possible via WiF and USB.
The high-quality technology inside the compact and modern GHL Doser 2.2, not only provides precise and simple dosing but also includes many more features. 
With the free GHL Connect App or the cloud service myGHL you can access your Doser from anywhere in the world to start dispensing programs or check the levels of your metering liquids.
The LED illuminated GHL Logo in the housing serves as a status indicator. It displays the condition of your aquarium by displaying various colors and tells you when something requires your attention.
Features
The milliliter precision and automated dispensing enable the dosing of liquids such as: 
Fertilizers
Trace Elements
Balling Salts
Lime WaterLiquid Feed
Integrated evaporated water refill (Auto Top–Off)
Water exchange of small water volumes
Stainless steel motor shafts (also suitable for the dosage of Iodine)
Chemical resistant tubing
Manual operation of each individual pump is possible
Pumps can be retrofitted
Individual parts can be replaced (tubes, pump head, motor)
24V stepper motors that allow micro doses of 0.1 mlUp to 150 doses per dayEasily chose dosing times via software (GHL Control Center).
Automatically: Up to 150 individual doses per day automatically distributed
Individually: Up to 8 doses per day individually se tEach pump can be set separately
Conveying capacity and dosing: 8-45 ml / minute (precisely adjustable to 0.1 ml)
Level indicatorWiFi, LAN, and USBAlarm function
Large LED status indicatorStatus LED for pumps
Convenient to program via our free PC software GCCOr over our app, web, and cloud service, also free of charge
Professional CAN Bus System ensures reliable and interference-free networking of all network devices.
Each pump can be operated manually via the push buttons on the front panel. This allows you to quickly post-dosing, deflating the tube vent or suctioning liquids.
Ample accessories available.

Technical specifications:

Color:
Black
 white
Dimensions: 220 x 150 x 75 mm (without pumps)
 
What's included:
 
Dosing pump unit SA (black or white)
power supply unit
USB Cable