# Key Concepts

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*   **`Strike`**

    * A system call that occurs every day at 00:00 UTC, determining the previous round's winner and loser positions. For example, if at strike time the ETH price is 3000 USDT, then a CALL position with a strike of 2600 is considered a winning position, while a PUT position with the same strike is considered a losing position.
    * Strike call is scheduled on Chainlink Automation
    * After each strike, the system sets five new strike prices for the next round. Winners and losers can redeem their shares accordingly.&#x20;
    *   Round Strike Calculation

        After each strike call, five new strikes will be generated for the next round.

        The price intervals between these five strikes will be 25 units each.


*   **`Round`**

    * The unit of time for managing positions. A round begins at 00:00 UTC, and the system automatically strikes at 00:00 UTC the following day to initiate the next round and set the next strike prices.


*   **`Round Window`**

    * An 18-hour period during which positions can be opened.


*   **`Expiration`**

    * A 24-hour duration from the start of one round to the next.


*   **`CALL & PUT`**

    * CALL: A position predicting that the next round’s ETH price will be higher than the strike price.
    * PUT: A position predicting that the next round’s ETH price will be lower than the strike price.


*   **`Shares`**

    * The unit of an options position. The minimum share quantity is 1, with no maximum limit on the number of shares that can be opened.


*   **`Leverage`**

    * When enabled, users can open positions with up to 100x leverage. The margin for leveraged positions comes from the liquidity pool. Leveraged positions carry higher risk, with the possibility of losing the entire margin.


*   **`Liquidity`**

    * Anyone can become an LP by depositing USDT into the margin pool. LPs earn rewards from liquidation events based on the amount of vPubShares they hold.


* **`LP Shares`**
  * Once a deposit is completed, the user receives corresponding ERC-20 LP shares (vPubShares) to claim rewards. The asset-share model follows the EIP-4626 standard.
