Germinas Boots, also known as Jackboots in the original PlayStation 2 version, are an accessory in Final Fantasy XII that make the wearer immune to Immobilize, and also provide large boosts to the wearer's Vitality and Speed in the Zodiac versions, making them one of the best accessories to equip for certain jobs.
In the original PlayStation 2 versions, Jackboots are sold for 600 gil in Lowtown's South Sprawl (after meeting Anastasis), Eruyt Village and Mt Bur-Omisace. They are found as a treasure in the rainy Giza Plains' Tracks of the Beast (50% chance to appear, 50% chance for gil, 50% chance the item treasure is Jackboots without the Diamond Armlet ), Ozmone Plain's Haulo Greens (in the south; 50% chance to appear, 40% chance for gil, 50% chance the item treasure is Jackboots without the Diamond Armlet ), and Golmore Jungle's Paths of Chained Light (southwestern bit; 55% chance to appear, 40% chance for gil, 50% chance the item treasure is Jackboots without the Diamond Armlet ). They are a rare steal from Judge Ghis, and a reward for the hunt for Cluckatrice.
In the updated Zodiac versions, the Germinas Boots cannot be bought from shops, but sell for 1,800 gil. They are found as a treasure in Lhusu Mines' Site 6 South (near the south exit to the save crystal in the small room; 25% chance to appear but is always the Germinas Boots), Henne Mines' Crossover C (always appears), and Subterra's Abyssal - North (70% chance to appear, 80% chance for gil, 50% chance the item treasure is Germinas Boots without the Diamond Armlet).
The Germinas Boots/Jackboots make the wearer immune to Immobilize, which makes the afflicted unable to move. An alternative would be to set up gambits for Esuna, but if the afflicted has magick or a ranged weapon, they can still attack and so the ailment is not as crippling as some others. Ribbons protect against all status ailments, but are also available late into the game. In the Zodiac versions, the Black Belt accessory protects against both Disable and Immobilize and is available much easier than the Germinas Boots.
Germinas Boots is one of the best accessories for jobs whose weapons use Speed in their damage calculations in the Zodiac versions for their enormous +50 Speed boost. They are great to equip on a Shikari wielding ninja swords, or an Archer wielding bows. Shikari with the Germinas Boots and the best ninja sword, is even superior to equipping the Genji Gloves. Ranged weapons can't combo, and thus Germinas Boots is the best damage-boosting accessory Archers can wear. It is worth seeking out the boots the earliest if using either job in the Zodiac versions, though with the added stat boosts the boots were also made much harder to find, all in optional dungeons. The earliest the player can get a pair is after the Antlion hunt and finding the Site 11 Key on the ground in Phon Coast's Hunters' Camp near a man sitting away from the populated area, to gain access to the deeper reaches of Lhusu Mines.
The Speed boost is less useful when wielding weapons other than the ninja swords or bows, and thus the character is likely better off wearing a different accessory unless they need the protection against Immobilize. The Hermes Sandals offer permanent Haste and a boost to Strength, and the player can also set up gambits for Haste and Hastega; however, both the Speed stat and the Haste status only affect how fast the ATB gauge fills, not how fast the character actually attacks, meaning they don't actually get that many more turns as most of one's "turn" is spend on attack/technick/spell animation; the best way to get more damage in fast is to deal combo hits.