I've found this unit difficult to use. Flashes E about 2 out of 5 times. Cuff is difficult to place in the proper position on either arm. It consistently registers 14 - 20 difference from Dr.'s office monitor. Comparisons were made in the Dr.s office and under her supervision. Even though Consumer Reports has it highly rated I did not find it accurate or easy to use. Would that it were not so. However, it is what it is.