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# Chains

The following Tempo chains are available:

```ts
import { Chain } from 'viem/tempo'

Chain.mainnet // [!code hl]
Chain.testnet // [!code hl]
Chain.devnet // [!code hl]
Chain.localnet // [!code hl]
Chain.moderato // [!code hl]
```

You can also import Tempo chains by name from `viem/chains`:

```ts
import {
  tempo, // [!code hl]
  tempoDevnet, // [!code hl]
  tempoLocalnet, // [!code hl]
  tempoModerato, // [!code hl]
} from 'viem/chains'
```

The `Chain` namespace also exports aliases for Tempo chains from `viem/tempo`:

```ts
import { Chain } from 'viem/tempo'

Chain.tempoMainnet
Chain.tempoTestnet
```

## Default Fee Token

Set a default fee token for a Tempo chain by adding a `feeToken` property to the chain definition or passing `feeToken` to `Client.create`.

Once set, all transactions will use this token as the default fee token, unless an override is provided at the transaction level.

```ts
import { Client } from 'viem/tempo'
import { tempoModerato } from 'viem/chains'

const chain = tempoModerato.extend({
  feeToken: '0x20c0000000000000000000000000000000000001',
})

export const client = Client.create({
  chain,
})
```