Suitable for use with single, dual, or twin element immersion heaters Bluetooth-enabled app for local control (Android and IOS) - Full smart control from anywhere with optional Wi-Fi adaptor that does not need a hub or gateway Easy to retrofit using the provided adaptor plate and fully interchangeable with all Horstmann/Secure Economy 7 and Electronic 7 controllers Measures estimated energy consumed for boost and off-peak in kWh via the app Includes 7-day programmer with 3 On Offs straight from the device, more can be added via the app Programmable boost - can be programmed so that it will heat only a small part of your tank at a set time each day Manual Boost button - ideal for 30 minutes, 1, or 2-hour top-up without changing the set program 7 years no quibble warranty