diff --git a/src/control_server.c b/src/control_server.c
index 92f2658..c144f8a 100644
--- a/src/control_server.c
+++ b/src/control_server.c
@@ -948,6 +948,7 @@ static void send_metrics(struct control_server* server, struct control_client* c
         link_info[i].keepalive_recv = (uint32_t)link->keepalive_recv_count;
         link_info[i].inflight_bytes = link->inflight_bytes;
         link_info[i].inflight_packets = link->inflight_packets;
+        link_info[i].inflight_lim_bytes = link->inflight_lim_bytes;
         link = link->next;
     }
     
diff --git a/tools/etcpmon/etcpmon_gui.c b/tools/etcpmon/etcpmon_gui.c
index 44904a3..ba81a0f 100644
--- a/tools/etcpmon/etcpmon_gui.c
+++ b/tools/etcpmon/etcpmon_gui.c
@@ -548,6 +548,9 @@ static void CreateControls(struct etcpmon_app* app) {
     app->hEditWaitAckTimer = CreateWindowExA(WS_EX_CLIENTEDGE, "EDIT", "",
         WS_CHILD | WS_VISIBLE | ES_READONLY | ES_CENTER,
         q_col1 + 195, qy - 2, 60, 18, hWnd, (HMENU)IDC_EDIT_WAITACK_TIMER, hInst, NULL);
+    app->hEditWaitAckOptInfl = CreateWindowExA(WS_EX_CLIENTEDGE, "EDIT", "",
+        WS_CHILD | WS_VISIBLE | ES_READONLY | ES_CENTER,
+        q_col1 + 260, qy - 2, 60, 18, hWnd, (HMENU)IDC_EDIT_WAITACK_OPT_INFL, hInst, NULL);
     
     /* ID metrics - row 4 */
 //    qy += 30;
@@ -1001,6 +1004,7 @@ void etcpmon_gui_update_metrics(struct etcpmon_app* app,
     UpdateEditIfChanged(hMain, IDC_EDIT_WAITACK_SUSP, "%s", metrics->etcp.wait_ack_cb_suspended ? "ON" : "OFF");
     UpdateEditIfChanged(hMain, IDC_EDIT_WAITACK_CB,   "%s", metrics->etcp.wait_ack_cb_set ? "ON" : "OFF");
     UpdateEditIfChanged(hMain, IDC_EDIT_WAITACK_TIMER, "%s", metrics->etcp.wait_ack_resume_timeout ? "ON" : "OFF");
+    UpdateEditIfChanged(hMain, IDC_EDIT_WAITACK_OPT_INFL, "%u", metrics->etcp.optimal_inflight);
     
     /* ID Metrics */
     UpdateEditIfChanged(hMain, IDC_EDIT_ID_NEXT_TX,    "%u", metrics->etcp.next_tx_id);
@@ -1057,7 +1061,7 @@ void etcpmon_gui_update_metrics(struct etcpmon_app* app,
             
             snprintf(line2, sizeof(line2),
                 "       RTT=%.1f ms, avg10=%.1f ms, TT=%.1f ms Timers: Init=%s, KA=%s, Shaper=%s | "
-                "KAsent=%u, KArecv=%u, InB/P=%u/%u",
+                "KAsent=%u, KArecv=%u, InB/L/P=%u/%u/%u",
                 (float)links[i].rtt_last/10.0f,
                 (float)links[i].rtt_avg10/10.0f,
                 (float)links[i].tt_last/10.f,
@@ -1067,6 +1071,7 @@ void etcpmon_gui_update_metrics(struct etcpmon_app* app,
                 links[i].keepalive_sent,
                 links[i].keepalive_recv,
                 links[i].inflight_bytes,
+                links[i].inflight_lim_bytes,
                 links[i].inflight_packets);
             
             SendMessageA(app->hListLinks, LB_ADDSTRING, 0, (LPARAM)line1);
diff --git a/tools/etcpmon/etcpmon_gui.h b/tools/etcpmon/etcpmon_gui.h
index 57079fd..d74b9d8 100644
--- a/tools/etcpmon/etcpmon_gui.h
+++ b/tools/etcpmon/etcpmon_gui.h
@@ -103,6 +103,7 @@ extern "C" {
 #define IDC_EDIT_WAITACK_SUSP   650
 #define IDC_EDIT_WAITACK_CB     651
 #define IDC_EDIT_WAITACK_TIMER  652
+#define IDC_EDIT_WAITACK_OPT_INFL 653
 
 /* ID Metrics control IDs */
 #define IDC_STATIC_IDS          640
@@ -250,6 +251,7 @@ struct etcpmon_app {
     HWND hEditWaitAckSuspend;
     HWND hEditWaitAckCb;
     HWND hEditWaitAckTimer;
+    HWND hEditWaitAckOptInfl;
     
     /* ID metrics */
     HWND hEditIdNextTx;
diff --git a/tools/etcpmon/etcpmon_protocol.h b/tools/etcpmon/etcpmon_protocol.h
index a924ddb..5996eb4 100644
--- a/tools/etcpmon/etcpmon_protocol.h
+++ b/tools/etcpmon/etcpmon_protocol.h
@@ -197,6 +197,7 @@ struct etcpmon_link_metrics {
     /* Inflight counters */
     uint32_t inflight_bytes;
     uint32_t inflight_packets;
+    uint32_t inflight_lim_bytes;
 };
 
 /* TUN interface metrics */