Each piece of equipment has common basic durability of 30, regardless of its rarity.

You can increase your equipment durability up to 40 by researching all relevant technologies in the "Blacksmithing" branch.

When item’s durability reaches 0, you can repair the item with silver. After each repair, the maximum durability of that item decreases by 1 (i.e. after 30 marches and a repair, your equipment durability will be 29/29).

The higher the gear's rarity, the more it costs to repair it.

Once the item's total durability reaches 0/1, you will no longer be able to equip nor repair it. However, you can extract from this item one of the materials that were used during crafting.