Warning: This product contains chemicals known to the State. The coolant recovery bottle acts as a reservoir for the engine’s cooling system. When coolant pressure exceeds the radiator caps springs rated pressure, excess coolant will overflow into the Recovery Tank. Once the engine has cooled down enough, vacuum is created in the coolant system and the coolant is sucked back into the coolant system. Features: Made with High Quality Aluminum for Enhanced Strength and Durability Replaces Factory Plastic Tank for a Heavier Duty Model Reuses Factory Hose, .100" Thick Aluminum Walls Package Includes: 1 x Coolant Recovery Overflow Tank Hardware as Shown in the Picture Above Compatible with: 02-07 Subaru WRX & STI