Product Details
Color Details
Size DetailsFrequently Asked Questions
Are the Maui Jim KAHANA MJ640 sunglasses available with prescription lenses?
What is MauiBrilliant lens material and how does it compare to glass?
What face shape and size do the KAHANA MJ640 sunglasses fit best?
What is PolarizedPlus2 technology and what protection does it provide?
How much do the KAHANA MJ640 sunglasses weigh?
What's the difference between the three lens options (Maui HT, Neutral Grey, and Maui Rose)?
Compare With Similar Frames
How the Maui Jim KAHANA MJ640 Sunglasses stacks up against the closest alternatives we carry.
- MauiFlex memory metal frame 'remembers' its shape and is highly durable
- Slightly larger 58mm lens width provides more coverage for medium to larger faces
- Lower price point ($268.50–$284.12 vs $291.26–$322.31)
- Significantly lower price ($159.63–$176.15)
- Stainless steel and Monel frame offers excellent durability
- Designed for larger faces with better coverage
- Large aviator frame designed specifically for bigger faces and wider coverage
- Similar price range ($235.60–$261.35) to KAHANA
- MauiBrilliant lens material with PolarizedPlus2 technology
Read the full comparison
Maui Jim KAHANA MJ640 vs GUARDRAILS MJ327 vs NA'AUAO MJ675
If you're choosing between Maui Jim's double-bridge aviator sunglasses, the decision comes down to frame material, fit, and budget. All three models feature the brand's acclaimed PolarizedPlus2 technology, but they differ in construction and target audience.
KAHANA MJ640: Premium Titanium for Narrow to Medium Faces
The KAHANA stands out with its titanium frame construction and MauiBrilliant lenses—the lightest, most advanced combination Maui Jim offers. The 53mm lens width with square aviator shape fits narrow to medium faces exceptionally well, and the signature Hawaiian engraving adds a premium touch. At $291–$322, it's the most expensive option here, but you're paying for titanium's corrosion resistance, featherweight feel, and refined aesthetics. Choose the KAHANA if you want the lightest possible frame, need prescription lenses (MauiBrilliant is the best prescription material), or prefer a modern square aviator over traditional teardrop shapes.
GUARDRAILS MJ327: Memory Metal Durability at a Lower Price
The GUARDRAILS uses MauiFlex memory metal, which "remembers" its original shape even after bending—ideal if you're hard on your sunglasses. The 58mm lens provides more coverage than the KAHANA, making it better for medium to larger faces. At $268–$284, it's the middle-ground option. The trade-off is slightly more weight than titanium and less refined finishing. Customer reviews are mixed on build quality, with some praising durability and others noting the frame feels less premium than expected. Choose GUARDRAILS if you need a larger fit, want memory metal's shape-retention properties, or prefer to save $20–$40 versus the KAHANA.
NA'AUAO MJ675: Budget-Friendly Classic Aviator
The NA'AUAO is the value pick at $159–$176—nearly half the price of the KAHANA. It features stainless steel and Monel construction with a traditional aviator teardrop shape designed for larger faces. You still get PolarizedPlus2 lenses and 100% UV protection, but the lens material and frame finishing aren't as advanced. The NA'AUAO is heavier and lacks the modern square aesthetic, but it's an excellent choice if you want proven Maui Jim optics without premium materials. Choose the NA'AUAO if budget is your primary concern, you prefer classic aviator styling, or you need a larger frame for better coverage.
Our Recommendation
For narrow to medium faces seeking the absolute best in lightweight comfort and optical clarity—especially if you need prescription lenses—the KAHANA MJ640 is worth the premium. Its titanium construction and MauiBrilliant lenses represent the pinnacle of Maui Jim's technology. If you need a larger fit or want memory metal durability, the GUARDRAILS MJ327 is a solid middle option. And if you're budget-conscious but still want authentic Maui Jim performance, the NA'AUAO MJ675 delivers excellent value in a classic aviator package.
At a Glance
Maui Jim GUARDRAILS MJ327 Sunglasses
Pros:
- MauiFlex memory metal frame 'remembers' its shape and is highly durable
- Slightly larger 58mm lens width provides more coverage for medium to larger faces
- Lower price point ($268.50–$284.12 vs $291.26–$322.31)
- Modified aviator shape with double bridge suits a wider range of face shapes
Cons:
- Memory metal frame is slightly heavier than titanium
- Less refined aesthetic compared to KAHANA's titanium construction
- No signature Hawaiian engraving details on frame
- Customer reviews note some quality inconsistency with frame materials
Maui Jim NA'AUAO MJ675 Sunglasses
Pros:
- Significantly lower price ($159.63–$176.15)
- Stainless steel and Monel frame offers excellent durability
- Designed for larger faces with better coverage
- Classic aviator styling with adjustable silicone nose pads and temple tips
- PolarizedPlus2 lenses with 100% UV protection
Cons:
- Heavier frame material compared to KAHANA's titanium
- Traditional aviator shape may not suit all face types as well as KAHANA's square design
- Less advanced lens material options
- No signature engraved details or premium finishing
Maui Jim CASTLES MJ728 Sunglasses
Pros:
- Large aviator frame designed specifically for bigger faces and wider coverage
- Similar price range ($235.60–$261.35) to KAHANA
- MauiBrilliant lens material with PolarizedPlus2 technology
- Classic aviator teardrop shape that's universally flattering
Cons:
- Larger size won't fit narrow or medium faces as well as KAHANA
- Traditional aviator shape lacks the modern square aesthetic of KAHANA
- Heavier overall due to larger lens and frame size
- May feel oversized for everyday casual wear