# IPeripheryImmutableState

Functions that return immutable state of the router

### Functions[​](https://docs.uniswap.org/contracts/v3/reference/periphery/interfaces/IPeripheryImmutableState#functions) <a href="#functions" id="functions"></a>

#### factory[​](https://docs.uniswap.org/contracts/v3/reference/periphery/interfaces/IPeripheryImmutableState#factory) <a href="#factory" id="factory"></a>

```solidity
  function factory(
  ) external returns (address)
```

**Return Values:**[**​**](https://docs.uniswap.org/contracts/v3/reference/periphery/interfaces/IPeripheryImmutableState#return-values)

| Type    | Description                           |
| ------- | ------------------------------------- |
| address | the address of the Uniswap V3 factory |

#### WETH9[​](https://docs.uniswap.org/contracts/v3/reference/periphery/interfaces/IPeripheryImmutableState#weth9) <a href="#weth9" id="weth9"></a>

```solidity
  function WETH9(
  ) external returns (address)
```

**Return Values:**[**​**](https://docs.uniswap.org/contracts/v3/reference/periphery/interfaces/IPeripheryImmutableState#return-values-1)

| Type    | Description          |
| ------- | -------------------- |
| address | the address of WETH9 |