How does the magnet work in Worms Reloaded?

I tried to launch the magnet on the terrain, it does some graphical effects and nothing more.

How does it work and when should you use it?

The "Electro Magnet" can either attract or repel metallic projectile weapons. You can press "Z" key before using/dropping it, to set the magnet to attract or repel.

They work modifying the parabola of metallic projectiles.

Also they can be destroyed after taking some damage.

Magnet affects Bazooka, Grenade, Cluster Bomb, Homing Missle, Holy Grenade, Mines, Air Strike and Bunk Buster.

The magnet repels projectiles like the bazooka.

After a few turns, it stops working. (Though it remains on the landscape and can be knocked around)