Latest Facebook Messenger 105 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; Android 5.0.1; LG-H440n Build/LRX21Y; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/46.0.2490.76 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/105.0.0.16.69;] Android 5 Spirit
Mozilla/5.0 (Linux; Android 4.4.2; LG-D722J Build/KOT49I.D722J10e) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/105.0.0.16.69;] Android 4 G3 Beat
Mozilla/5.0 (Linux; Android 4.4.2; GT-I9301I Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/105.0.0.16.69;] Android 4 Galaxy S III Neo