When you purchase this key, you get to choose which of the 7 items you want. This is not luck based.

In the server, you can choose one of these:

• Enchanted Netherite Helmet
• Enchanted Netherite Chestplate
• Enchanted Netherite Leggings
• Enchanted Netherite Boots
• Enchanted Netherite Sword
• Enchanted Crossbow
• Enchanted Mace

The armor can give you more protection which makes it easier to survive while the tools can help you mine blocks faster.