# How are “relays” defined in PoS Ethereum?
**URL:** https://collective.flashbots.net/t/how-are-relays-defined-in-pos-ethereum/148
**Category:** Searchers
**Tags:** question
**Created:** [August 24, 2022, 3:16am UTC](https://collective.flashbots.net/t/how-are-relays-defined-in-pos-ethereum/148 "2022-08-24T03:16:47Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@brock](https://collective.flashbots.net/u/brock)
#### Post date: [August 24, 2022, 3:16am UTC](https://collective.flashbots.net/t/how-are-relays-defined-in-pos-ethereum/148/1 "2022-08-24T03:16:47Z")
Before the merge, mev-relay (commonly referred to as “the relay”) was responsible for accepting bundles from searchers and relaying them to miners.
After the merge, the term “relay” will mean something entirely different. _These_ relays are a component of PBS – they’re responsible for escrowing blocks from builders for validators. With mev-boost, validators choose the most profitable block from a number of relays. Each relay keeps the contents of a block private until the validator commits to proposing it to the network for inclusion.
Specifically, relays do the following:
- accept new blocks from builders
- send header of most profitable block to a validator upon request
- _the validator locks in their commitment to propose the full block by signing this header_
- send full block to validator after receiving block header signed by the validator
- perform all of this quickly and reliably, so that validators don’t miss proposal deadlines
For a deeper explanation of mev-boost and relays, Check out @thegostep’s _[ethresear.ch post](https://ethresear.ch/t/mev-boost-merge-ready-flashbots-architecture/11177)_.
For more information about how bundles are sent post-merge, see [this forum post](https://collective.flashbots.net/t/how-will-sending-bundles-change-in-pos-ethereum/147).
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### Author:  [@metachris](https://collective.flashbots.net/u/metachris)
#### Post date: [August 24, 2022, 9:14am UTC](https://collective.flashbots.net/t/how-are-relays-defined-in-pos-ethereum/148/2 "2022-08-24T09:14:22Z")
I’d deprecate the term “bundle relay” as this only leads to confusion, and is not a relay in the sense it was in eth1, where bundles were relayed to miners. In PoS, bundles will be sent to builders instead.
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### Author:  [@brock](https://collective.flashbots.net/u/brock)
#### Post date: [August 24, 2022, 8:50pm UTC](https://collective.flashbots.net/t/how-are-relays-defined-in-pos-ethereum/148/3 "2022-08-24T20:50:25Z")
Good call @metachris. Rewrote it, I think it’s much clearer now.