purchase the 305 when I finally get feed up with the runkeeper app force closing on my droid . I love be able to glance at my wrist and see my pace . I live in the middle of nowhere and it have only `` lose '' satellite when I go into a brick building at a nature center . once i be back outside it pick up quickly and I continue my run . I have not use all the feature yet but love have it . Pretty neat to use the heart rate monitor too . battery cover on the monitor do chafe -lrb- instruction book tell you this -rrb- , need to use lube , I keep tuck my tshirt under it lol . will not be use the monitor often , but still a neat feature . Great little gadget : -rrb-