Maretron SAE 5-Bolt Pattern Focus Tube w/Dead Band Eliminator [TFTDBE-5H]SAE 5 Bolt Pattern Focus Tube w Dead Band Eliminator Focus tubes allow the TLM100 TLM150 ultrasonic tank level monitors to be used for level measurement on vessels with non displacement hulls at up to 15 of pitch or roll, compared to 6 pitch or roll for the sensor alone. Additionally, the focus tube with deadband eliminator raises the TLM100 TLM150 2" above the top of the tank, allowing accurate level measurement with fluid levels all the way to the