Latest Mobile Silk 61 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; Android 5.1.1; KFTBWI Build/LVY48F) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.2.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 5 Fire HD 10
Mozilla/5.0 (Linux; Android 5.1.1; KFMEWI Build/LVY48F) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.2.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 5 Fire HD 8 (2015)
Mozilla/5.0 (Linux; Android 5.1.1; KFFOWI Build/LVY48F) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.2.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 5 Fire 7"
Mozilla/5.0 (Linux; Android 5.1.1; KFARWI Build/LVY48F) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.2.1 like Chrome/61.0.3163.98 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/61.2.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 4 Kindle Fire HDX 7" WiFi
Mozilla/5.0 (Linux; Android 4.4.3; KFSOWI Build/KTU84M) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.2.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 4 Kindle Fire HD 7" WiFi
Mozilla/5.0 (Linux; Android 4.0.3; KFTT Build/IML74K) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.4.2 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 3 Kindle Fire HD
Mozilla/5.0 (Linux; Android 4.0.3; KFTT Build/IML74K) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.3.1 like Chrome/61.0.3163.98 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/61.4.2 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 3 Kindle Fire
Mozilla/5.0 (Linux; Android 4.0.3; KFOT Build/IML74K) AppleWebKit/537.36 (KHTML, like Gecko) Silk/61.3.1 like Chrome/61.0.3163.98 Safari/537.36 Fire OS 3 Kindle Fire