We recommend and only support TAF-1680X filament based, 6V incandescent lamp bulbs for your HST. We find that the TAF-1680X Lamps gives out the optimal performance needed and match the original analog KA and KC bulb specs, a brighter lumen and just as long if not longer lasting. 1680X lamp bulbs are also used throughout all our in-house qualification and standardization procedures. TAF-1680X lamp bulbs come in 10 bulbs per box. With 200 hours of service life per lamp pair, each box offers 1,000 hours of estimated service life. Bulk order limits may apply due to limited supply. You are using the correct bulbs when you see this label on the box. You are using the correct bulbs when you see this label on the box. Our upgraded Lamp Socket Fit Kits fits with ceramic standoffs and allows for voltage isolation and to eliminate accidental shortages. Upgraded Lamp Socket Mounts are steel construction inserts that fit into most older chimney’s. Their positive voltage ceramic standoffs eliminate the need for the previous ceramic bases that were subject to breaking. Measurement sensor cable clamp prevents accidental pulling and dislodging the terminals that can cause faulty analog readings. Clearly marked connections for easier re-assembly or rebuild should you need to replace or clean a sensor. Becareful not to over torque things. New Socket Mounts allow for cleaner lamp cable routing in the can to prevent them from interfering with lamps or sensors.