QTI manufactures Mil-Spec and Space Level thermistors for high cost of failure applications. They make both fully assembled and tested temperature probes as well as discrete temperature sensor components.
Quality Thermistor – QTI – https://www.qtisensing.com/
They also have NTC custom temperature probes, RTD Probes, precision USB thermometer and The Hydroguard IP68 series that combines a highly stable precision thermistor with an extremely durable waterproof housing.
Platinum RTD Probes are available in a variety of probe styles and materials. RTD Probes
RTD Temperature Sensors
These have high temp wire insulation and ceramic potting compound in a.flat end brass temperature sensor housing. They make 100 ohm, 500 ohm and 1,000 ohm RTD elements in this type.
QTI Sensing Solutions
2108 Century Way Boise, Idaho 83709-2862 USA