Due to my HLT setup, and the temperature probe being short and small OD, I had to replace it. I needed to remove the sensor included and install a QD connection (from another source) that also allowed me to use an 8' line to go to the sensor (12' version is available too). This then went to a 1.5" TC PT100 sensor into my Spike+ HLT. I was going to try and use the included sensor, but it would have protruded a fraction of an inch into the HLT once I put it into a fitting. IMO, useless. Luckily, the QD connection item I purchased went directly into the hole used by the included sensor. So no drilling was needed. As mentioned, my new sensor connection has a longer cable length, giving me more options for later. Granted, I'll be limited by the 4' power cord length to the element. I would advise going to a standard RTD quick connection at the panel so that customers can then get the senor they want without issue. Plus without needing to remove the (IMO) useless sensor provided. I suppose I could have dropped the sensor through the lip of the HLT, but that didn't seem wise.