When added to a RO system can produce 99.99% pure water with 0 TDS reading

The De-ionization filter takes the full size RO to a higher level of filtration. It is an excellent inline filter insert, especially for those who live in areas with exceptionally high levels of TOTAL DISSOLVED SOLIDS (TDS) in their tap water.
The post de-ionizer takes the small percentage of contaminants that the membrane could not remove and filters this to greater than 99.99% pure water.
It will give you 0 ppm TDS, Conductivity attainable less than 0.1uS/cm or resistivity of close to 18 meg.ohm 
DI (de-mineralize) resin filter: Produce 99.99% pure water by simply attaching this convenient deionization filter with RO unit.
Convenient post RO filtration DI unit (RO/DI unit) provides crucial supplemental filtration to remove most impurities for pure polished product water. Excellent in areas with hard water. Produce 99.99% pure water. It will give you 0 ppm TDS, Conductivity attainable less than 0.1uS/cm.
Technical Specifications:
Diameter: 2.5"
Length: 10"
pressure: 4bar
Capacity: 500 gallons (2000 liters)
Approx 6 Months
Fits standard 10" Housing not supplied with insert

* Postage & Package of £6.00 & 2% Administration & bank charges included in the price