This is a particular requirement for applications such as in aircrafts, ships, hospitals, etc. The absorbent glass mat also gives flexibility in battery shape design. Batteries can be made circular or in many other shapes to conserve space.
The Absorbent Glass mat has a low resistance. The batteries based on AGM (Absorbent Glass Mat) do not require maintenance. The Absorbent Glass Mat also prevents sulphation (the deposit of sulphates on the electrodes). This minimizes the need for topping the charge in the batteries.
AGM batteries are also vibration resistant.
The disadvantages of AGM batteries are their high cost. They also have low specific energy and are sensitive to overcharging.