The HR5 can be custom programmed in minutes by the user. Easily create new species programs, Isoflurane overdose, CO2 only, The concentrations and durations of CO2 and Isoflurane are what you decide. Your system arrives factory programmed for Mice,Rat or, Pup. Waste gas is absorbed by a charcoal filter or can be vented. One charcoal filter is included.