This block is an alternative to redstone dust. Differences:
- It is a standalone block - it doesn't need a support.
- Any block can be placed on it.
- Propagates signal instantly.
- It emits a 'weak' redstone signal only.
- It doesn't have a facing, so all blocks around it will be powered, unlike with redstone dust.
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.