Product buy early 2014, tests power with professional voltmeter 10 OK batteries at the reception. 4 used batteries and 9 months later they are already HS and the 6 remaining in the box no longer have power. Originally intended for use in radios alarm clocks to keep the memory of the hour or smoke detectors, I highly recommend this product that should work between 3 and 5 years without difficulty, very bad value for money.