03/06/2015. Great spare cuff. Because these cuffs are factory sealed and you cannot identify when they fail (all such things do in time) it's prudent to have a spare unit to test and compare when BP readings begin to get erratic. I check my BP daily every morning and keep a running track with the "Lose It!" app on my iPhone 5s. My old OMRON BP machine (HEM-780RELN2) was becoming very erratic and I have replaced it with  a OMRON BP791IT model that uses the same cuff.  Testing the old model with the new cuff isolates the failures to the BP machine, not the cuff, so I am able to assure that replacing it was a prudent action. Plus now I have two spare cuffs for futures use, as needed.