A full wiki going through the features of the mod can be found here.

Information

Extra Shields is a vanilla+ expansion to shields. It adds various new shields inline with the vanilla armor system and shield plating upgrades and also includes new and improved enchantment support.

Extra Shields has been carefully crafted to ensure it remains inline with vanilla progression.

Check out More Shield Variants's Compatability Add-on, it works well with Extra Shields.

Shields & Plated Shields

Each material in vanilla now has a shield variant! You can also plate these shields to increase the durability at the cost of a longer cooldown if you're attacked with an axe.

Shields and their Plating items.

Shield Repair Kit

The shield repair kit can be used to quickly repair your shield whilst in combat, be careful though, as using a repair kit will permemantly reduce the total durability of the shield it's used on.

Crafting Recipes

For more information on crafting recipes, take a look at the following wiki pages:

Enchantments

Bracing: Decreases the cooldown when the shield is disabled by an axe attack.
Momentum: Gives the player a brief speed boost when their shield is disabled.
Evokering: Found in woodland mansions, Evokering will introduce a chance for evoker fangs to spawn underneath attackers when the player blocks an attack.
Launching: Found in ominous vaults (rare loot), Launching will have a chance to launch attackers away from the player when the shield is disabled.
Lifebound: Found in nether fortress bridge chests, players will have a chance to absorb health from the attacker when the player blocks an attack.

All of these enchantments have been tested and balanced extensively, some are not compatible with others.

For a more in depth look into enchantments and their incompatibilities, take a look at the wiki.