Designed for emergency repairs while travelling.  This kit includes parts that could be damaged while travelling:-
Replacement electrictronic water in fuel sensor suits all Diesel Water Watch units
Seal kit containing all seals in the Diesel Water Watch in the WW200722 unit
Replacement shatter proof bowl which fits the WW20072 Diesel Water Watch
 
Diesel Water Watch is a robust water in fuel contamination detection device, but if you are travelling it pays to have back up parts which may fail due to on road damage or the need to repeatedly drain your Diesel Water Watch.  While you can by-pass the Diesel Water Watch if it fails, which leaves you unprotected from Diesel Fuel Contamination, it is preferential to maintain your fuel systems safety and keep your Diesel Water Watch in working order.  A small price to pay for piece of mind.