Mind enlightening me to the purpose of such instrument ?
Probably HERMS/RIMS.
What's it's max temp rating, and where did you buy it?
As previously mentioned they are used for measuring flow rates. Slightly different versions exist for liquids and gasses, but they are basically the same in principle.
I am going to be attaching this to my RIMS rocket so i can monitor my dough in rate (which i run through the RIMS rocket to ensure my strike temp is dead on), then monitor my recirculation flow rate, and finally my lauter flow rate.
It's rated up to 200F. McMaster P/N 4400K63. Mfr P/N Blue-White Industries F-45376L-8. It took me a long time to find this one. Most of the time they are very pricey since their target market is industrial. This is the only one i could find that had a high enough temp spec, the right range, correct fittings, and a reasonable-ish price.