The Linen Cuirass is a low ranked heavy armor in Final Fantasy XII that boosts the wearer's Defense by 14 (Zodiac) or 13 (original), and Strength by 4. It is metallic for the purposes of the Magnetize debuff present in the boss battles against Vinuskar and Ultima.
In the updated Zodiac versions, the Linen Cuirass is sold for 1800 gil in Rabanastre, Bhujerba and Dalmasca Westersand after the events at Ondore's Estate, and by Dyce in Nam-Yensa Sandsea, Tomb of Raithwall, and Balfonheim Port. It is found as a treasure in Ogir-Yensa Sandsea's Primary Tank Complex (75% chance to appear, 20% chance for gil, 50% chance the item treasure is the Linen Cuirass without the Diamond Armlet equipped), as well as in Trial Mode Stage 36 with the Diamond Armlet equipped. It is still the rare drop from the Wyvern and the Bellwyvern on the Cerobi Steppe.
Linen Cuirass is a low level helm giving 14 or 13 Defense depending on version, and 4 Strength. The strength bonuses make heavy armor ideal for frontline fighters, though the HP boost from light armor can be valuable in the beginning of the game. Linen Cuirass is a good helm to equip over any inferior equipment the player may have on anyone who attacks physically, although a gun-wielder does not benefit from the strength-boost.
In the Zodiac versions, Uhlan, Knight, Time Battlemage, and Foebreaker can equip it, and so it is only useful to buy if the player has chosen these License Boards as a party member's first job. It is a good heavy armor for the part of the story where the party crosses the sandseas and ventures into the tomb.