A couple of years ago, McMurdo set the bar high with a personal locator beacon the size of a pack of cigarettes (if anyone remembers what that looks like). ACR answered the challenge this year with the 4.6-ounce ResQLink ($325), claiming the title as the smallest PLB in the world. With the addition of a 406link .com subscription, the unit also functions as an “I’m OK” e-mail or text message check-in device.