OEM RESOL FKP6 PT1000 1000 ohm probe type sensor. This is the sensor that s packaged with RESOL controllers. Compatible with RESOL, Steca, Stiebel Eltron SOM, & other solar controls that use PT1000 standard sensors. Stainless probe measures 6mm in diameter, 50mm in length. High temperature 1.5m silicone wire. Temperature range -50C to 200C (-58F - 356F).