diff --git a/mintlify/payouts-and-b2b/payment-flow/send-payment.mdx b/mintlify/payouts-and-b2b/payment-flow/send-payment.mdx
index d75dc913..3bd5db6a 100644
--- a/mintlify/payouts-and-b2b/payment-flow/send-payment.mdx
+++ b/mintlify/payouts-and-b2b/payment-flow/send-payment.mdx
@@ -74,12 +74,17 @@ curl -X POST 'https://api.lightspark.com/grid/2025-10-13/transfer-out' \
       "accountId": "InternalAccount:a12dcbd6-dced-4ec4-b756-3c3a9ea3d123"
     },
     "destination": {
-      "accountId": "ExternalAccount:e85dcbd6-dced-4ec4-b756-3c3a9ea3d965"
+      "accountId": "ExternalAccount:e85dcbd6-dced-4ec4-b756-3c3a9ea3d965",
+      "paymentRail": "ACH"
     },
     "amount": 12550
   }'
 ```
 
+<Tip>
+  The `paymentRail` field is optional. If omitted, Grid selects a default rail for the destination. Specify a rail (e.g., `ACH`, `WIRE`, `RTP`, `FEDNOW`) when you need to control which payment network processes the transfer.
+</Tip>
+
 
 ```json Success (201 Created)
 {
diff --git a/mintlify/snippets/sending/same-currency.mdx b/mintlify/snippets/sending/same-currency.mdx
index f5e7da37..8bbe0075 100644
--- a/mintlify/snippets/sending/same-currency.mdx
+++ b/mintlify/snippets/sending/same-currency.mdx
@@ -32,11 +32,15 @@ curl -X POST 'https://api.lightspark.com/grid/2025-10-13/transfer-out' \
   -H 'Content-Type: application/json' \
   -d '{
     "source": { "accountId": "InternalAccount:a12dcbd6-dced-4ec4-b756-3c3a9ea3d123" },
-    "destination": { "accountId": "ExternalAccount:e85dcbd6-dced-4ec4-b756-3c3a9ea3d965" },
+    "destination": { "accountId": "ExternalAccount:e85dcbd6-dced-4ec4-b756-3c3a9ea3d965", "paymentRail": "ACH" },
     "amount": 12550
   }'
 ```
 
+<Tip>
+  The `paymentRail` field is optional. If omitted, Grid selects a default rail for the destination.
+</Tip>
+
 ```json Success (201 Created)
 {
   "id": "Transaction:019542f5-b3e7-1d02-0000-000000000015",