They go on the new slot added, "arms" slot in your inventory. You make them by doing this:
(mushroom = redstone)
You make 1 like this, which increases reach by 2. If you have 2 equipped, it increases your reach by 4. This is very useful for building. If you build a lot with these on, they run out of durability.
(mushroom = redstone)
You make 1 like this, which increases reach by 2. If you have 2 equipped, it increases your reach by 4. This is very useful for building. If you build a lot with these on, they run out of durability.