Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Sci-fi Military Pack Pro Free.
Sci-fi Military Pack Pro v1.0
The Sci-fi Military Pack Pro contains all the models you need to start the development of your sci-fi game, may it be a RTS, a FPS, or any other kind of games!
The pack consists of 11 low poly with high resolution textures models, ensuring that you get the maximum quality with the minimum performance impact.
The polycount is between 2500 and 5000 tris for all the units; except the biggest ones (Gun Lord and Skyshadow) which have a higher polycount. The textures are 2048*2048.
This pack contains the following:
-Avian hunter (anti-air unit)
– Blacktrack (big 3 canons tank)
– Brain Bucket(recon vehicle)
– Fire Rain (artillery)
– Ghostwind (troop transport)
– Gun Lord (Huge moving fortress with 10 weapons and troop transport)
– Thunder track (gatling gun tank)
– Avian (jet fighter)
– Skyshadow (flying fortress helicopter)
– Gatling turret
– Missile Turret