The Repeater

The repeater is a vanilla redstone component that propagates a signal fed in through its back. When it does this, it introduces a 1-tick delay. Clicking on the repeater will adjust the delay, which can last for up to 4 ticks.
A repeater can be "locked" by placing another powered repeater outputting directly to its side. When locked, a repeater will not change its output.

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Redstone Repeater