Board Thread:Tutorials/@comment-5885957-20121218102627/@comment-5390323-20130129065329

Forcefields are impenetrable. Only 5 things can get through forcefields: catalytic lens (or lesser equivelant), wireless redstone, ender chest items, teleporters (item and player), and ComputerCraft rednet. Maybe I can find 2 other things that can get through, but not much can. If you set up your field right, not even these can get in.