These temperature probe ends are made from 304L stainless steel. (316 stainless steel is available for customers looking to use them in a salt water aquarium) One end of the temperature probe end is sealed by spinning the end shut and then sealing it with a TIG weld.  No fluxes or fillers are used, the stainless is just fused together. The OD is .25" to fit most all thermowells available and the material is .028" wall. They will fit any T-092 case device such as the Dallas Maxim DS18B20, DS18S20 or DS1820 temperature sensors. It will also fit LM34 and LM35 series temperature sensors. They are a very tight fit for maximum thermal conductivity to the sensor.

If you are building your own temperature sensor, these are the temperature probe ends you want. They will fit the ID of the our thermowells for use in a carboy or conical or they can be mounted directly to almost any other vessel by using a 1/4" tube compression to NPT adapter in which case a thermowell is not needed. If you are using a compression adapter, use an o-ring instead of the compression ring unless you plan on a permanent installation. These are temperature probe ends only and do not include any electronics.

Which length should you get?

I recommend the 4" or 6" temperature probe end if you are using them in tubing or plumbing fittings like tees or the ends of chillers or if they are going to be inserted into a thermowell like a fermenter. If you are going to use the temperature probe with a compression adapter, then get a longer probe like 8" to 12", depending on the width of the vessel. Using an o-ring in place of the compression ring on the fitting allows you to slide the temperature probe deeper or shallower into the vessel. 

If you don't see the length you're looking for, shoot us an email.  I've made stainless temperature probe ends to 24".  Past 36" they get more difficult to ship but it's possible.  I've also made them welded into NPT fittings and tri clover fittings.