Dayrock Armor is armor made of Dayrock (obviously). Each part of the armor set is 345 uses in durability, meaning the whole armor is 1380 uses in durability. The parts have different abilities.
Dayrock Helmet is a helmet (obviously). It is made of Dayrock like mentioned but has Glowstone in the top. It gives off light (why will it not give light if it has glowstone?) and is useful for walks in caves or searches for more Dayrock, Nightrock or Diamonds. It will only give off light while it still has durability, 0 giving off no light, and will only give off light when you are in the dark.
Dayrock Chestplate is a chestplate (obviously). It is made of Dayrock like mentioned. It gives you the ability to absorb most of the damage from most resources. Dayrock Chestplates are useful for protection. It only absorbs damage when it still has durability, 0 being useless against all resources of damage.
Dayrock Leggings give you the ability to sprint faster and protect you from getting hungry when you sprint. Dayrock Leggings are useful for long no-minecart-no-boat races. It only speeds up sprinting when it has more than 0 durability, 0 giving you no abilities and turning the sprint to normal and allows you to get hungry again.
Dayrock Boots give you the ability to double-jump by attempting to jump again while you're in the air. Double-jumping height depends on how much your inventory weighs, similarly to pressure plates that send an output the strength of how much the activating event (such as an entity collision or wooden plate detecting an arrow) weighs. Double-jumping with no inventory items allows you to jump to 12 blocks in the air. Dayrock Boots, when double-jumping, causes the player to leave light cyan smoke particles, like Nightrock Boots which leaves navy ones instead. It only allows double-jumping as long as you have above 0 durability, 0 while in a double-jump causes you to suddenly fall down very quickly, and attempting to double-jump again will not work.
Fixing armor will be similar to fixing other armor, tool and sword types. It will reset durability. It can also be fixed by placing them alone shapelessly in the crafting window or table, resetting durability like normal.