The JBL Aquarium Thermometer Mini is very suitable for all small aquariums, such as Nano aquariums. With a total length of only 60 mm it is not disturbing in the tank and a good readability is nevertheless guaranteed. JBL Aquarium Thermometer Mini+ precise measurement for healthy fish: mini thermometer has fine measuring scale with a 2C gradation+ easy to install: attach with suction cup (also suitable for clamping onto JBL CristalProfi m internal filter)+ safe: blue, non-toxic alcohol filling (instead of mercury)+ scale from 0 to 50C+ length: 60 mm, diameter: 5 mm