diff --git a/options/custom/desktops/niri/input.nix b/options/custom/desktops/niri/input.nix
index a860689..0f4881c 100644
--- a/options/custom/desktops/niri/input.nix
+++ b/options/custom/desktops/niri/input.nix
@@ -33,11 +33,11 @@ in {
             repeat-rate = 40;
           };
 
-          # BUG: Applies to trackball device, switch to "flat" when per-device configuration is supported
+          # TODO: Update when per-device configuration is supported
           # https://github.com/YaLTeR/niri/issues/371
           # https://github.com/sodiboo/niri-flake/blob/main/docs.md#programsnirisettingsinputmouseaccel-profile
           mouse = {
-            accel-profile = "adaptive";
+            accel-profile = "adaptive"; # flat
             accel-speed = -0.7;
             scroll-factor = 1.25;
           };
@@ -55,8 +55,10 @@ in {
           # https://github.com/sodiboo/niri-flake/blob/main/docs.md#programsnirisettingsinputtrackballaccel-profile
           trackball = {
             accel-profile = "adaptive";
-            accel-speed = -0.5;
+            accel-speed = -0.8;
+            left-handed = true;
             middle-emulation = true;
+            natural-scroll = true;
           };
         };
       }
diff --git a/options/custom/services/udev.nix b/options/custom/services/udev.nix
index 47a24f8..c94ba6e 100644
--- a/options/custom/services/udev.nix
+++ b/options/custom/services/udev.nix
@@ -6,19 +6,46 @@
 }:
 with lib; let
   cfg = config.custom.services.udev;
+
+  chgrp = getExe' pkgs.coreutils "chgrp";
+  chmod = getExe' pkgs.coreutils "chmod";
 in {
-  options.custom.services.udev.enable = mkOption {default = false;};
+  options.custom.services.udev = {
+    enable = mkOption {default = false;};
+    backlight = mkOption {default = true;};
+    input = mkOption {default = true;};
+  };
 
   config = mkIf cfg.enable {
     # https://wiki.archlinux.org/title/Udev
-    # Allow video group to change display brightness
-    # https://raw.githubusercontent.com/ErikReider/SwayOSD/main/data/udev/99-swayosd.rules
-    services.udev.extraRules = let
-      chgrp = "${pkgs.coreutils}/bin/chgrp";
-      chmod = "${pkgs.coreutils}/bin/chmod";
-    in ''
-      ACTION=="add", SUBSYSTEM=="backlight", RUN+="${chgrp} video /sys/class/backlight/%k/brightness"
-      ACTION=="add", SUBSYSTEM=="backlight", RUN+="${chmod} g+w /sys/class/backlight/%k/brightness"
-    '';
+    services.udev.extraRules =
+      optionalString cfg.backlight ''
+        # Allow video group to change display brightness
+        # https://raw.githubusercontent.com/ErikReider/SwayOSD/main/data/udev/99-swayosd.rules
+        ACTION=="add", \
+          SUBSYSTEM=="backlight", \
+          RUN+="${chgrp} video /sys/class/backlight/%k/brightness"
+        ACTION=="add", \
+          SUBSYSTEM=="backlight", \
+          RUN+="${chmod} g+w /sys/class/backlight/%k/brightness"
+      ''
+      + optionalString cfg.input ''
+        # Per-device input configuration
+        # https://wiki.archlinux.org/title/Libinput#Via_Udev_Rule
+        # https://wayland.freedesktop.org/libinput/doc/latest/device-configuration-via-udev.html
+        #?? sudo libinput list-devices
+        #?? sudo udevadm info /dev/input/event*
+        #?? sudo udevadm trigger /dev/input/event*
+
+        # Kensington Orbit
+        ENV{ID_USB_SERIAL}=="Kensington_ORBIT_WIRELESS_TB", \
+          ENV{ID_INPUT_MOUSE}="", \
+          ENV{ID_INPUT_TRACKBALL}="1"
+
+        # ProtoArc EM04
+        ENV{ID_USB_SERIAL}=="Nordic_2.4G_Wireless_Receiver", \
+          ENV{ID_INPUT_MOUSE}="", \
+          ENV{ID_INPUT_TRACKBALL}="1"
+      '';
   };
 }