It makes the 4-4 TU. Without them the 4-4 would still be a balancer, just not a TU one. [virtual-signal=signal-1] If you take two regular 4-4's [virtual-signal=signal-2] and combine them, you'd get a TU 4-4. [virtual-signal=signal-3] But two of the splitters are redundant, so they can be removed. [virtual-signal=signal-4] The result looks like you've just added two splitters at the end.