diff --git a/ControlBooth/Services/USBTree.swift b/ControlBooth/Services/USBTree.swift
index 36f4c9f..74b6ea9 100644
--- a/ControlBooth/Services/USBTree.swift
+++ b/ControlBooth/Services/USBTree.swift
@@ -22,6 +22,9 @@ nonisolated struct USBTreeRow: Identifiable, Equatable, Codable {
     /// True when the hub it is plugged into can switch this port's power on
     /// its own (uhubctl's `ppps`), so this is something that can be power cycled.
     var selectable: Bool
+    /// True for a hub uhubctl lists as `ppps`: it can switch each of its own
+    /// ports' power. False for other hubs and for devices that aren't hubs.
+    var switchesPorts: Bool = false
 }
 
 /// Builds the USB tree from the IORegistry (`ioreg -a -p IOUSB -l`), marking
@@ -86,7 +89,8 @@ nonisolated enum USBTree {
             isHub: isHub, isRTLSDR: isRTL,
             parentPath: parent?.path, parentUSBID: parent?.usbID,
             port: parent == nil ? nil : Int(path.split(separator: ".").last ?? ""),
-            selectable: parent?.switchesPorts ?? false))
+            selectable: parent?.switchesPorts ?? false,
+            switchesPorts: isHub && hubs.contains { $0.location == path && $0.usbID == usbID && $0.switchesPerPort }))
         let hub = hubs.first { $0.location == path && $0.usbID == usbID }
         let me = Parent(path: path, usbID: usbID, switchesPorts: hub?.switchesPerPort ?? false)
         for child in children { walk(child, depth: depth + 1, parent: me, hubs: hubs, into: &rows) }
diff --git a/ControlBooth/Views/USBTreeView.swift b/ControlBooth/Views/USBTreeView.swift
index f2066b7..76f3adf 100644
--- a/ControlBooth/Views/USBTreeView.swift
+++ b/ControlBooth/Views/USBTreeView.swift
@@ -80,6 +80,15 @@ struct USBTreeView: View {
             if !row.serial.isEmpty {
                 Text(row.serial).font(.caption.monospaced()).foregroundStyle(.secondary)
             }
+            if row.isHub {
+                Label(row.switchesPorts ? "per-port power" : "no per-port power",
+                      systemImage: row.switchesPorts ? "bolt.fill" : "bolt.slash")
+                    .font(.caption2)
+                    .foregroundStyle(row.switchesPorts ? Color.green : .secondary)
+                    .help(row.switchesPorts
+                          ? "uhubctl can switch each port of this hub on its own (ppps)."
+                          : "uhubctl can't switch this hub's ports individually (ganged, or not listed).")
+            }
             Spacer()
             if let port = row.port, let parent = row.parentPath {
                 Text("\(parent) port \(port)").font(.caption).foregroundStyle(.secondary)
diff --git a/ControlBoothTests/USBTreeTests.swift b/ControlBoothTests/USBTreeTests.swift
index 51f465b..6bd224d 100644
--- a/ControlBoothTests/USBTreeTests.swift
+++ b/ControlBoothTests/USBTreeTests.swift
@@ -70,6 +70,13 @@ struct USBTreeTests {
         #expect(USBTree.rows(fromIORegPlist: plist, hubs: []).allSatisfy { !$0.selectable })
     }
 
+    @Test func onlyPerPortSwitchableHubsAreFlagged() {
+        let rows = USBTree.rows(fromIORegPlist: plist, hubs: hubs)
+        // 2-2.1 is the only hub uhubctl lists as ppps; the others are ganged or devices.
+        #expect(rows.filter(\.switchesPorts).map(\.path) == ["2-2.1"])
+        #expect(USBTree.rows(fromIORegPlist: plist, hubs: []).allSatisfy { !$0.switchesPorts })
+    }
+
     @Test func rtlsdrsBelowAPortLosePowerWithIt() throws {
         let rows = USBTree.rows(fromIORegPlist: plist, hubs: hubs)
         let mtt = try #require(rows.first { $0.path == "2-2.1.1" })