The ACR ResQLink PLB 375 is a reliable and durable personal locator beacon with positive reviews for its ease of use, waterproof design, and powerful satellite signal. It's a subscription-free device that is activated by deploying the antenna and pressing a button. Key features include built-in GPS for accurate location, a 406 MHz signal to alert search and rescue, and a strobe light for nighttime visibility.  Requires 5 year battery replacement. DIY batteries with easy replacement instructions available on eBay and Amazon for about $18. Includes sealable waterproof case for marine use.