This AGM battery from Victron has a capacity of 12V and 110Ah.
AGM stands for Absorbed Glass Mat. In these batteries, the electrolyte is absorbed in a glass fiber mat that is clamped between the plates.
In an AGM battery, the charge carriers, hydrogen ions and sluate ions, move more easily between the plates than in a GEL battery. This makes an AGM battery more suitable for the short-term supply of very high current than a GEL battery and therefore suitable for bow thrusters, starter motors, heavy inverters, etc.
In closed batteries, the oxygen gas formed on the positive plates moves to the negative plates where, after a complicated chemical reaction, it recombines with hydrogen to form water.