Splash Proof oxygen analyser.
The VN202 Analyser offers the diver ease of use, reliability, and flexibility.

This small lightweight hand held instrument has been specifically designed, by Nitrox divers who have over 25 years experience of Oxygen monitoring, for the diving environment.

The VN202 has a degree of 'Water Proofing' which although not guaranteed to be 100% waterproof it should survive exposure to the severe splashing encountered by divers.
 

Analyser with sensor just   £155
Analyser with DIN KIT (inc.  Quick-Ox),  and case -   £179

The Quick-Ox was designed to help measure the oxygen concentration in a sub-aqua diving cylinder more accurately and quickly with almost any analyser and should increase sensor life. 
Go-Dive price for Quick-Ox on its own £14.99
Link to Divernet Quick-Ox review

The DIN Kit enables gas sampling from Pillar valves with DIN thread  
includes DIn adapter fitting, Quick-Ox and tubing with connector.
Go-Dive price for DIN Kit on its own £29.99