PurposeTo be attached to TSF FTIT213022 or ST9999-VB to create vacuum in the system for detecting leaks at windows, doors and hatches, drain valves as per following: D6-36367 (for 747, 767, 777) FTIU2130 sht 0601 (for 747) FT1W2130 (for 777)Used WithST9999-VB, ST9999VBA-1TypePressure gage 