Minecraft wiki entry for Best_enchantments_guide, associated text: Note: More than 20 Enchantment Protection Factor (EPF) is useless. 1 Level of Protection = 1 EPF, 1 Level of specific type of Protection = 2 EPF. For example, two pieces of armor with Blast Protection IV (EPF 8 each) and a single piece with Protection IV (EPF 4) would give a total EPF of 20 versus explosions.