Universal Brake Master Cylinder Sight Glass Set – 10 Pieces with O-Rings

Keep a clear eye on your brake fluid levels with this 10-piece Brake Master Cylinder Sight Glass Set. Designed as a universal replacement for most motorcycles and ATVs, each kit includes a durable resin lens and a rubber O-ring seal, giving you everything you need for a leak-free, crystal-clear view of your brake pump reservoir.

Key Features

Clear Resin Lens: Thickened, high-transparency resin construction delivers an unobstructed view of brake fluid levels — no guesswork, no leaks.
Durable Rubber O-Ring: Each sight glass comes paired with a resilient rubber O-ring featuring strong rebound and aging resistance for a reliable, long-lasting seal.
Universal Fit: Compatible with the majority of motorcycles and ATVs — a go-to replacement for worn or damaged brake master cylinder windows.
Comprehensive Value Pack: 10 complete sets (lens + O-ring) in one package — enough spares to keep on hand for future maintenance needs.
Easy Installation: Drop-in replacement design makes swapping out old or cloudy sight glasses straightforward, even for home mechanics.

Specifications

Available Sizes: 12mm / 14.5mm / 18mm
Package Quantity: 10 sets (sight glass + O-ring each)
Lens Material: High-clarity resin
Seal Material: Durable rubber
Compatibility: Universal – most motorcycles and ATVs
Country of Origin: Made in China

Note: Please allow 2–3% dimensional variance due to manual measurement. Actual color may vary slightly from images depending on monitor settings.

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Safe Riding Resources

For general motorcycle safety tips and best maintenance practices, visit the National Highway Traffic Safety Administration or review brake system inspection guidelines at CPSC.gov.

Frequently Asked Questions

Q: What sizes are included in the brake master cylinder sight glass set?

A: The sight glasses are available in three sizes — 12mm, 14.5mm, and 18mm — to suit a wide range of motorcycle and ATV brake master cylinder reservoirs. Please measure your existing sight glass before ordering to ensure the correct fit.

Q: Are these sight glasses compatible with my motorcycle or ATV?

A: Yes — these brake master cylinder sight glasses are designed as universal replacements compatible with most standard motorcycles and ATVs. They feature a straightforward drop-in design, making installation simple for most riders and home mechanics.

Q: How does the O-ring seal prevent fluid leaks?

A: Each sight glass comes with a high-quality rubber O-ring engineered for strong rebound and aging resistance. When correctly seated, the O-ring creates a tight seal around the sight glass window, effectively preventing brake fluid from seeping out of the reservoir.

Q: Why do I need to replace my brake master cylinder sight glass?

A: Over time, sight glasses can become cloudy, cracked, or develop worn seals, making it difficult to accurately monitor brake fluid levels. A clear, properly sealed sight glass is essential for maintaining visibility of your brake fluid and ensuring safe, confident braking performance on every ride.