Patented thimble ceramic element.More than 20 years ago, Bosch developed the heated Thimble Type Oxygen Sensor. Since that time, Bosch has improved and updated these oxygen sensors to make them more effective, more durable and easier to install.
Bosch Premium Thimble Type Oxygen Sensors utilize an electrical heating element inside the thimble-shaped end to bring the sensor up to operating temperature in less than a minute.