Timex is celebrating National Runners Day tomorrow by asking folks to tweet or post to Instragram with the #IMARUNNER hashtag. For every time the hashtag is posted, Timex will donate $5 (up to $15,000) towards One Fund Boston which provides relief to those affected by the Boston Marathon tragedy. In addition, Timex will also give away 60 of its Ironman performance watches to runners who share the hashtag.

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