Bluelab In-Line pH ProbeThe Bluelab In line pH Probe is a replacement probe for use with Bluelab Guardian Monitor Connect In line. It can be screwed directly into female 1" NPT pipe fittings using the included adapter. Threaded probe head allows for simple installation direct into an irrigation line for effective in line measurements. The high pressure rates pH probe has a pressure rating of 7 bar pressure or 100 psi. Liquid flow naturally cleans the flat pH measurement