Latest Mobile Silk 48 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; Android 5.1.1; KFMEWI Build/LMY47O) AppleWebKit/537.36 (KHTML, like Gecko) Silk/48.2.2 like Chrome/48.0.2564.95 Safari/537.36 Fire OS 5 Fire HD 8 (2015)
Mozilla/5.0 (Linux; Android 5.1.1; KFARWI Build/LMY47O) AppleWebKit/537.36 (KHTML, like Gecko) Silk/48.2.2 like Chrome/48.0.2564.95 Safari/537.36 Fire OS 5 Fire HD 6
Mozilla/5.0 (Linux; Android 4.4.3; KFTHWI Build/KTU84M) AppleWebKit/537.36 (KHTML, like Gecko) Silk/48.2.2 like Chrome/48.0.2564.95 Safari/537.36 Fire OS 4 Kindle Fire HDX 7" WiFi
Mozilla/5.0 (Linux; Android 4.0.3; KFTT Build/IML74K) AppleWebKit/537.36 (KHTML, like Gecko) Silk/48.2.2 like Chrome/48.0.2564.95 Safari/537.36 Fire OS 3 Kindle Fire HD
Mozilla/5.0 (Linux; Android 4.0.3; KFOT Build/IML74K) AppleWebKit/537.36 (KHTML, like Gecko) Silk/48.2.2 like Chrome/48.0.2564.95 Safari/537.36 Fire OS 3 Kindle Fire