EnvironicsĀ® Gas Mixers and Gas Blenders automatically blend gases to generate precise gas calibration standards, create gaseous atmospheres or produce gas mixes for research or production purposes. Each component concentration may be independently varied. With an accuracy of better than +/- 1% and repeatability of +/- .05% of setpoint, the Series 4000 can produce concentrations from percent levels to ppb for single or multi-point calibration.