TECO N310 Series - Keypad in singles:

Chapter 6 Peripherals Components
6-6
(3) Keypad in singles:
1. Screw (M3)
2. N310 KeyPad
3. Fixing panel (t=1~6mm)
4. Unit: mm；Tolerance: ±0.2mm
2-∅ 3.5 M3 nut fixation or,
2-M3 panel screw thread fixation