I have a total of 8 bottles of hair developers all new and all professional. They are different brands and different volumes. I have the following developers as per this list:
WELLA ColorTouch Intensive Emulsion - 4% Vol 13
WELLA ColorTouch Intensive Emulsion- 19% Vol 6
Kenra Color Demi Permanent- 9 Vol
2 Kenra Color Permanent - 20 vol
Pro Care Gentle Lift Creme Deveolper stabilized formula - vol 10