diff --git a/core/types/tx_blob.go b/core/types/tx_blob.go
index 351eee78f9..b5789eea32 100644
--- a/core/types/tx_blob.go
+++ b/core/types/tx_blob.go
@@ -176,6 +176,8 @@ func (sc *BlobTxSidecar) Copy() *BlobTxSidecar {
 	}
 }
 
+// BlobTxCellSidecar is a sidecar that carries cells instead of blobs.
+// The Custody field represents which cells of each blob this sidecar contains.
 type BlobTxCellSidecar struct {
 	Version     byte
 	Cells       []kzg4844.Cell