Motorcycle brake master cylinder oil cup and brake fluid reservoir made from CNC machined aluminum for reliable performance. Durable and long service life: Compared with plastic reservoirs, this aluminum tank is sturdier and more resistant to wear and impact. Clear fluid level visibility: The transparent interior allows you to easily monitor brake fluid level, while an internal rubber Oring seal helps prevent leaks. Easy installation: Simple replacement with no special tools required; designed for straightforward installation and use. Practical benefits: Improves durability, provides clear fluid monitoring, and reduces the risk of leaks compared with standard plastic reservoirs. Use scenarios: Upgrading a stock plastic brake fluid reservoir on a sport or street motorcycle to improve durability and visibility. Replacing a worn or damaged reservoir during routine brake maintenance to ensure reliable fluid containment. Replacing or refreshing the reservoir during brake fluid flushes to easily monitor levels and prevent leaks during service.