In Quake 4, Convoys (known as Rollers in the game files) are sentry guns shaped like orbs dropped by Hornets. When such unit hits the ground, it begins rolling around until it finds a safe position to attack. When it does, it'll stop and open fire with two Machine Guns that come out of the interior through the metallic shell. If a target gets too close, a convoy unit will retreat and find another safe spot to attack from.
- Convoys are very easy to destroy, since they will not retreat if attacked at a moderate range. One hover tank cannon shot or a volley of missiles will destroy a Convoy. It'll take some time for a Machine Gun to destroy a Convoy, so using it is not efficient. It is possible to destroy them by running them over with a heavy vehicle; however they will roll away into safety if a target gets too close. While rolling, it doesn't take any damage, since some kind of forcefield is protecting it. You'll have to wait for it to stop moving to start shooting.
- With other Strogg units present, Convoys prove to be a nuisance. They are not as dangerous as other Strogg units, so stronger targets like a Heavy Hover Tank or a Hornet should be prioritized, stay away from them for a distance to your own advantage whenever it can.