Some users have experienced short sensor (191-211) life when using high tin content no lead solders. The high percentage of tin may attack the sensor wire causing failure after only a few measurements. The 191-212 sensor wire is specially coated near the weld junction to improve sensor life when using no lead solders. Depending on the solder composition the standard sensor (191-211) may be acceptable. 10 pieces of sensor wire for use with 191 and 192 thermometer. Sensors are specially coated to better withstand no lead solders. - The 191-212 sensor wire is specially coated near the weld junction to improve sensor life when using no lead solders. It has a special metal alloy coating that resists corrosion and oxidation.