# isPieceCID

> **isPieceCID**(`cid`): `cid is PieceLink`

Defined in: [packages/synapse-core/src/piece.ts:240](https://github.com/FilOzone/synapse-sdk/blob/6cf8b3ed2dd3ae76ed05cb86995d711a08a298a6/packages/synapse-core/src/piece.ts#L240)

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