Latest Facebook 51 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; U; Android 4.3; en-us; SCH-R950 Build/JSS15J) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy Note II
Mozilla/5.0 (Linux; U; Android 4.3; en-au; GT-I9300T Build/JSS15J) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy S III
Mozilla/5.0 (Linux; U; Android 4.2.2; es-cl; LG-D805 Build/JDQ39B) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.2 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 G2
Mozilla/5.0 (Linux; U; Android 4.2.2; en-in; Micromax A114 Build/JDQ39) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 A114
Mozilla/5.0 (Linux; U; Android 4.1.2; pt-br; LG-E455f Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 E455f
Mozilla/5.0 (Linux; U; Android 4.1.2; es-us; GT-I8260E Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy Core
Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SCH-R530U Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy S III LTE
Mozilla/5.0 (Linux; U; Android 4.1.2; en-gb; LG-P715 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Optimus L7 II
Mozilla/5.0 (Linux; U; Android 4.1.2; en-au; LG-P713 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Optimus L7 II
Mozilla/5.0 (Linux; U; Android 4.0.4; en-us; LG-LS840 Build/ZVK.IMM76D) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Viper 4G LTE
Mozilla/5.0 (Linux; U; Android 4.0.4; de-de; HTC Incredible S Build/IMM76D) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Incredible S
Mozilla/5.0 (Linux; U; Android 4.0.3; en-us; LG-L40G Build/IML74K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 L40G
Mozilla/5.0 (Linux; Android 5.1.1; LG-H445 Build/LMY47V; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/46.0.2490.76 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 5 Escape 2
Mozilla/5.0 (Linux; Android 5.0.2; HTC Desire 826 dual sim Build/LRX22G) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/37.0.0.0 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 5 Desire 826 Dual SIM
Mozilla/5.0 (Linux; Android 4.4.2; SM-G313MY Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy Ace 4
Mozilla/5.0 (Linux; Android 4.4.2; SM-C111M Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 Galaxy K zoom
Mozilla/5.0 (Linux; Android 4.4.2; G735-L12 Build/HuaweiG735-L12) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/51.0.0.14.10;] Android 4 G Play
Mozilla/5.0 (iPad; CPU OS 9_3_5 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Mobile/13G36 [FBAN/FBIOS;FBAV/51.0.0.52.154;FBBV/25351091;FBDV/iPad2,5;FBMD/iPad;FBSN/iPhone OS;FBSV/9.3.5;FBSS/1; FBCR/;FBID/tablet;FBLC/en_US;FBOP/1] iOS 9 iPad Mini
Mozilla/5.0 (iPad; CPU OS 7_1_2 like Mac OS X) AppleWebKit/537.51.2 (KHTML, like Gecko) Mobile/11D257 [FBAN/FBIOS;FBAV/51.0.0.52.154;FBBV/25351091;FBDV/iPad4,2;FBMD/iPad;FBSN/iPhone OS;FBSV/7.1.2;FBSS/2; FBCR/Carrier;FBID/tablet;FBLC/en_US;FBOP/1] iOS 7 iPad Air
Mozilla/5.0 (iPad; CPU OS 10_3_4 like Mac OS X) AppleWebKit/603.3.8 (KHTML, like Gecko) Mobile/14G61 [FBAN/FBIOS;FBAV/51.0.0.52.154;FBBV/25351091;FBDV/iPad3,6;FBMD/iPad;FBSN/iPhone OS;FBSV/10.3.4;FBSS/2; FBCR/;FBID/tablet;FBLC/ru_RU;FBOP/1] iOS 10 iPad 4