I have both but only use the mms2 now as I am off the tools and only use it for inspections. Mms2 is more compact but on scan mode the readings do not relate to anything other than protimeters own scale. Cmex2 - scan mode readings are accepted by some manufacturers and relate to known scales. It was my preferred set for testing when I was on the tools. Both will do rh tests. I have a cmex2 kit with loads of extras I will be selling as I no longer need it. Sent from my LG-H850 using Tapatalk