we have have two of these product for the past three year . they perform well , do the job , and for 10 buck , I think they be a good deal . I have read the other review , but we experience with the 40001 alarm have be good -- I have carry this with I on travel , and never miss a appointment . there be detailed instruction at the -lrb- ... -rrb- website -- with good battery and the instruction these clock do the job well .