# Epoch Concept The epoch is the central unit of time in the tokenomics. An epoch is one calendar month, so it lasts 28, 29, 30 or 31 days depending on the month. It is used to determine the [ParaBoost](/governance/parallel-governance-token-prl/tokenomics/paraboost) calculation period and to manage the [fee sharing](/governance/parallel-governance-token-prl/tokenomics/fee-distribution) distribution to sPRL1 and sPRL2 holders. On-chain, the `RewardMerkleDistributor` does not set the epoch length: its `EPOCH_LENGTH` constant of 28 days is only the shortest claim window it accepts for a published epoch. :::info The cooldown applied when unstaking sPRL1 and sPRL2 is **not** one epoch. It is a separate, fixed period of 28 days on Ethereum and Base (one day, without penalty, on the sunset Polygon and Sonic deployments and the paused sPRL2 v1 vault), held per staking contract as `timeLockDuration` and changeable by governance within a 1 to 365 day range. See [Staking Mechanisms](/governance/parallel-governance-token-prl/tokenomics/staking-mechanisms). :::