FT 011 Tamperproof (Pre‑set) Thermostats are available in two color‑coded configurations with fixed setpoints. The FTO 011 provides a normally closed contact (red ‑ opens on temperature rise) for regulating heaters or for switching signal devices when temperature has fallen below the minimum value. The FTS 011 provides a normally open contact (blue ‑ closes on temperature rise) for regulating filter fans, heat exchangers, cooling devices or for switching signal devices when temperature limit has been exceeded.