I would calibrate with 7.01 using the front adjuster and 4.0 using the back adjuster. Having two set points makes it more accurate. Every 6 months or so i clean and calibrate three controllers. IME the older probes, that may need replacing, seem not to calibrate to the 4.0. I will be replacing a 4 year old one soon. If anyone knows of any good deals let me know.