Ultrasteel Direct Slimline with one of the smallest footprints from the unvented cylinders on the market today, has been designed to heat the water using two electric immersion heaters - smart immersion fitted as the primary heat source with secondary immersion suitable for use with low tariff electricity. It is the ideal choice for those ‘tight’ installations where space is limited and a small footprint is essential, and is ideal for use in all electric buildings or properties off the gas grid.