For the past fifteen years, Sonys portable radios have dominated a very specific market: the federal prison. One specific model, the SRF-39FP (the FP stands for federal prison), remains a firm favorite 15 years after its debut. Its made out of clear plastic, allowing guards to ensure the radios arent being used to smuggle contraband, lasts for forty hours on a single AA battery, and is rated by enthusiasts as one of the most precise portable radios around. In a New Yorker article, Joshua Hunt looks at how and why the SRF-39FP became the iPod of prison.