Absorbent glass mat (AGM) is a class of VRLA lea-acid battery in which the electrolyte is absorbed into a fiberglass mat. The plates in an AGM battery may be flat like wetcell lead-acid battery, or they may be wound in a tight spiral. Their unique (for lead acid chemistries) construction also allows for the lead in their plates to be purer as they no longer need to support their own weight as in traditional cells. Their internal resistance is lower than traditional cells due to close plate proximity and the pure lead plates have lower resistivity, they handle higher temperatures better, and self discharge more slowly.