That's a thermistor. Matrix Orbital uses Dallas One Wire probes. It won't work.

This is what I am currently using Henry:

http://www.procooling.com/users/phaestus/temp/probes%20001.jpg

Just sealed up with Plumber's Goop.

You might want to work out something a little more professional like:

http ...

You can buy "T" fittings that are threaded on the inside. I would think that a T with 1/4" NPT threads on the inside of all three ends would be best. That way people can use either 3/8" or 1/2" barbs depending upon their cooling system. You'll have to come up with a way to tighten down the temp ...