I buy my 305 a couple of year ago and while the battery be still fine , the watch be no longer functional . of the two other folk I know of who have 305 's , both be also experience the same basic failure - the watch become intermittent and eventually stop work all together . the root of the problem appear to be a couple of thing - the weedy metal contact use between the two watch half tend to get bent out of shape and lose contact and the watch be not particularly water proof . when mine fail , it get intermittent for a couple of run -lrb- would either fail to turn on , or would randomly turn off during the run and could not be power on again -rrb- . poke around online reveal that this be a common problem with the watch so I open it up and attempt to apply the fix suggest -lrb- lightly bend the contact back into place -rrb- . unfortunately , when I open the watch up -lrb- it be just glue together lightly , another bad design choice -rrb- it be clear that water\/sweat have get into the watch and have corrode the interior and the contact . since the contact be so fragile I break a couple of they off try to clean they and bend they back into shape . in all other aspect , it be a nice improvement over the 201 I have before -lrb- which I be back to use now -rrb- . the main reason I have upgrade to the 305 be for the more sensitive receiver since my 201 have a horrible time lock the satellite where I run . if it be not for the poor construction quality , I would heartily recommend it .