# isPieceCID

```ts
function isPieceCID(cid): cid is PieceLink;
```

Defined in: [packages/synapse-core/src/piece.ts:253](https://github.com/FilOzone/synapse-sdk/blob/1d6c4b9fe34534bf1087dfe41491b72be0b46858/packages/synapse-core/src/piece.ts#L253)

Check if a CID is a valid PieceCID

## Parameters

| Parameter | Type | Description |
| ------ | ------ | ------ |
| `cid` | `Link` | The CID to check |

## Returns

`cid is PieceLink`

True if it's a valid PieceCID