This BW Technologies by Honeywell REG-DF-1 Demand Flow Regulator has a maximum output capacity of 3 liters per minute, so it can be used to calibrate up to 8 docks simultaneously. Do not connect more than 4 docks to a single cylinder of calibration gas while using this demand flow regulator. Regulators sold each.
See TnA Safety, Webster, NY on MacRae's Blue Book