Robinair Cool-Tech ID Plus Refrigerant Identifier Go and "No Go" lights clearly show if refrigerant is pure enough to be recovered or charged Signals "Go" only if refrigerant is 98% pure Hydrocarbon alarm protects the user by signalling if potentially dangerous butane, propane, etc., is present in the refrigerant Displays percent of air in the A/C system or tank For R-12 and R-134A