BW Technologies Quad Gas CH4 (1.25% / 50% LEL), O2 (18.0%), H2S (25ppm), CO (100ppm)

If you use the recommended 0.5lpm regulator, the calibration procedure should take approximately 2 minutes. That makes it 1 ltr per calibration. It's a 34ltr cylinder. I see that you chose the cylinder with the Pentane Equivalent. You may need that but I wanted to point it out as BW normally uses Methane unless the Pentane is needed specifically.