diff --git a/usb_application/constants.py b/usb_application/constants.py
new file mode 100644
index 00000000..d4c1fd42
--- /dev/null
+++ b/usb_application/constants.py
@@ -0,0 +1,13 @@
+from array import array
+
+CMD_SEL_ROOT = array('B', [0xA0, 0xA4, 0x00, 0x00, 0x02, 0x3F, 0x00])
+CMD_SEL_FILE = array('B', [0xA0, 0xA4, 0x00, 0x00, 0x02, 0x7F, 0x20])
+CMD_GET_DATA = array('B', [0xA0, 0xC0, 0x00, 0x00, 0x16])
+# SuperSIM ATR
+atr_supersim= array('B', [0x3B, 0x9A, 0x94, 0x00, 0x92, 0x02, 0x75, 0x93, 0x11, 0x00, 0x01, 0x02, 0x02, 0x19])
+
+# Faster sysmocom SIM
+ATR_SYSMOCOM1 = array('B', [0x3B, 0x99, 0x18, 0x00, 0x11, 0x88, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x60])
+ATR_SYSMOCOM2 = array('B', [0x3B, 0x99, 0x11, 0x00, 0x11, 0x88, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x60])
+NEW_ATR = ATR_SYSMOCOM2
+