Scales are a rare item in Reign of Giants. They are dropped by the Summer Giant, Dragonfly. Scales are used to craft fire-resistant items: the Scalemail, which grants wearer immunity to fire damage, and the fire-proof container, the Scaled Chest.
Don't Starve TogetherEdit
In Don't Starve Together, Scales can also be used to craft Scaled Flooring, and the Scaled Furnace. The flooring limits the rate that fire spreads to objects placed on it, and the furnace is an infinite light and heat source similar to Magma.