from this site -
http://www.hychill.com.au/
HR12 is a blend of R600a and R290, two naturally occurring hydrocarbon refrigerant gases and is perfect for use in automotive air-conditioning systems and in refrigeration applications.
HyChill HR12 is derived from uniquely pure natural gas sources, and manufactured to the strictest quality controls.
HR12 is efficient and safe to use, requiring no modification to air conditioning systems and minimal modification to most refrigeration systems.
HyChill HR12 ensures exceptional energy efficiency, dispersing heat much more effectively than fluorocarbon equivalents.
Substantial cost savings for long term operation are achievable by replacing fluorocarbon refrigerants with HR12.