Robinair 34788NI Premier R-134A Refrigerant Recovery, Recycling and Recharging Machine Program to recover, vacuum, leak test and charge without operating panel valves Display reminds you to empty the graduated container to show the amount of oil to replace Visual and audible alarm notifies the user when service is complete, or if a problem has occurred Automatic air purge eliminates system-damaging air without monitoring gauges or opening valves Automatic refrigerant refill feature maintains a user-selectable amount of refrigerant in an internal vessel and signals when it's time to change supply tank, no monitoring required