A type K thermocouple is the most common general purpose thermocouple. Compared to other thermocouple types, these are fairly rugged and cost-friendly. However, they will have a slightly shorter life span than other thermocouple types, such as the more expensive Type S. Type K thermocouples will have red and yellow extension wires, and can be used up to 1260 °C /2300 °F This product is thermocouple only, but a thermocouple block and extension wire can be ordered as separate items. The 6" refers to the length of the probe on the thermocouple. The important factor in determining which length thermocouple is appropriate for a kiln is the size of the kiln wall.