American Lube TIM-MTL-42 42" Long Black Steel Downtube, 1-1/2" NPT (M) CouplingsAmerican Lube TIM MTL 42 Suction Tubes Are Made From Black Steel Pipe. The Tubes In This Chart Are Based On Using No Check Valve. Subtract 5" From The Tube Length If Using A 9: 1 Low Level Cutoff. If Using A 9: 1 Series 425 Pump Order Tim 161 Pipe Coupler Separately To Connect The Suction Tube To The Pump. 42" Long Black Steel Downtube For 5: 1 Thunder Pump Or 9: 1 Pump. 1 1 2" Npt (M) Thread On Both Ends.