The best headphones, watches, and apps for half-marathon runners

The RBC Brooklyn Half Marathon, which takes place in May every year, is a fun 13.1-mile course. You spend the first half battling hills in the shade and beauty of Prospect Park, only to swap that for a new challenge during the second half of the race — the ease of a relatively low-grade downhill trek on the shadeless, hot Ocean Parkway. The race's relaxed hill promises a PR for many runners, while the daunting heat dusts other runners into a PW. Last year, I hit the former; this year, the latter.