Features: Temperature measurement used in pool pond fish tank. Maximum temperature minimum temperature memory function. Indoor temperature and humidity display. Outdoor temperature display. Outdoor high degree of waterproof performance. Descriptions: It has Calendar, Clock, Alarm. There are & 8451; and & 8457; to choose. It is 30m waterproof, which sis suitable for using in the spa, bathtub or swimming pool. Specification: Distance between sensor and the host : 100 meters Frequency: 433 Hz Outdoor temperature range: -40 & 8451; ~ 60 & 8451; Temperature sensor response time: 48 seconds Indoor temperature range: 0 & 8451; ~ 50 & 8451; Host sensors can detect three channels Temperature range in swimming pool: -40'C~60'C (-40'F~140'F) Wireless transmission range: 100m transmitter uses 2 x AA batteries (not included ) The receiver uses 2 x AAA batteries (not included ) Material : ABS Product Machine size : 12*7.5*2.2cm Package size : 17*13.5*10.3cm Package Content: 1 x Wireless Pool Spa Hot Tub Thermometer 1 x Remote Sensor