Signal Cable

This block is an alternative to redstone dust. Differences: Note that Signal Cable can activate redstone dust, but cannot be activated by it. To overcome this limitation, you can just put a repeater between them.
 * 1) It is a standalone block - it doesn't need a support.
 * 2) Any block can be placed on it.
 * 3) Propagates signal instantly.
 * 4) It emits a 'weak' redstone signal only.
 * 5) It doesn't have a facing, so all blocks around it will be powered, unlike with redstone dust.