Tape & Reel (TR) is the package size of NTC thermistors. It's in the 0603 package for convenience. NTC thermistors can operate reliably at 125°C because of their maximum operating temperature. It is recommended that NTC thermistors operate at a minimum temperature of -55°C for relibility reasons. In order for the NTC thermistors to operate correctly, the 2 pins must be connected.