Shock resistant heater thermostats in particularly slender shape and with protection against overheating The sera delta heater thermostats are made of shock resistant glass and hardly consume space in the aquarium due to their slender shape. The adjustment range of the heater thermostats is between 18 and 32°C (64 - 90°F). The protection against overheating provides additional safety. It switches off automatically if the heater heats up outside the water. The clearly visible status display shows the operational status in 3 colors: green (temperature OK), red (heating), violet (protection against overheating is on). The extra long 1.8 meter (6 ft.) cable makes installation easier and allows forming a drip loop.