Pinpoint Monitors....Any good?

Anybody using any of the Pinpoint monitors in their tank? I'm looking for some 1st hand reviews. Specifically on the Ph, salinity, and calcium monitors. Are they accurate? A must have item? Or not worth the money?



Also, I was interested in the ORP monitor, but to be honest I'm not exactly sure how they work. What are you looking for with the readings? Are they only useful if running ozone?