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 be used to craft Scaled Flooring, the Scaled Furnace and a Dragonfly Figure. The flooring limits the rate that fire spreads to objects placed on it, while the furnace is an infinite light and heat source similar to Magma.