How thick are EPDM membranes?

We sell a total of five roofing systems. Four are EPDM membranes and the fifth is a Polyurathane Liquid. The thicknesses are listed below:

• ClassicBond
  1.2mm (Standard)
  1.5mm (Premium)
• RESITRIX
  2.5mm
• ClassicBond Pro
  2.54mm
• Skyguard
  1.0mm