I found this site
Reflectix Product Summary
which had these details:
Product Name: Reflectix
Insulation Classification: Radiant heat reflector
Thickness As Tested: .28"
Claimed "R" Value: 8.3 to 14.3 depending on type of installation.
Actual "R" Value (at product thickness): .67
Equivalent "R" Value (per inch): 2.38