For Power Back-up Systems, such as Inverter and Solar-Power Systems, the Tall Tubular (Maintainable) Wet-Cell Battery is a more recent development. They are more rugged, more durable and have been designed to have more Cyclic life (which is much needed for Power Back-up Systems). Compared to their Maintenance-free or Dry-Cell Counterpart. Their impeccable performance are as a result of the rigorous Research and Development that have been applied to their Production. With Our Tall Tubular (Maintainable) Wet-Cell Batteries, there are no wastage at all, as only the required Energy is released at a time, when needed, whilst the unused Energy is stored-up, retained for long period of time and made available whenever required. However, depending on usage, they require topping or gauging with Distilled Water roughly every Six(6) Months. They have a lifespan of Five(5) Years plus, and we normally give One(1) Year and Six(6) Months warranty, expressly for them. The Satlex range of Tall Tubular (Maintainable) Wet-Cell Batteries are excellent value for money.