RESOL FKP4/H 1000 ohm high temperature probe type sensor. Compatible with RESOL, Steca, Stiebel Eltron SOM & other solar controls that use PT1000 standard sensors. High temperature range model. Stainless probe measures 4mm in diameter, 40mm in length. High temperature 1m silicone wire. Temperature range -50C to 250C (-58F - 482F). This sensor is recommended for the panel sensor in evacuated tube drainback systems.