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The Ray-Ban Kai RB3757 sunglasses bring a fresh take on '90s-inspired oval frames with modern sustainability built in. These unisex metal sunglasses feature a sleek, narrow oval shape that works especially well on smaller faces—a fit that's hard to find in many contemporary designs. The full-rim stainless steel frame comes in polished gold, gunmetal, and silver finishes, each paired with color-contrast temple tips that add a subtle edge to the classic silhouette.
Bio-Based Lenses for Clearer Vision
Ray-Ban engineered the Kai with bio-based polyamide lenses containing 40% renewable carbon content sourced from castor oil. These lenses deliver excellent optical clarity and 100% UV protection while reducing reliance on fossil-based materials. Available in solid green, dark violet, dark grey, and mirrored yellow flash gold, plus a polarized azure option, the lenses offer both style variety and real sun protection. The bio-polyamide material is lightweight, impact-resistant, and provides sharp vision without the chromatic distortion found in lower-grade plastics.
Fit and Features
The RB3757 measures 56mm or 59mm lens width with a 15mm bridge and 145mm temples. Adjustable nose pads let you dial in the perfect fit, and the single-bridge design keeps the look clean and minimal. These frames are prescription-ready, so you can add your Rx lenses without sacrificing the design. The oval shape is versatile enough for everyday wear but distinctive enough to stand out—a balance Ray-Ban has refined over decades.
Whether you're drawn to the retro vibe, the sustainable materials, or simply need a quality pair of metal sunglasses that fit a smaller face, the Kai RB3757 delivers on all three fronts.
Product Details
Product DetailsModel
0RB3757Shape
Gender
Material
Bridge Type
Rim Type
Age Group
Color Details
Color DetailsFrame Color
GoldColor Code
9213/2Color Description
Pale GoldLens Color
Green
Color Code
004/69Color Description
GunmetalLens Color
Dark Violet
Frame Color
GoldColor Code
921387Color Description
Pale GoldLens Color
Dark Grey
Color Code
004/2VColor Description
GunmetalLens Color
AzureLens Features
polarized
Frame Color
GoldColor Code
9213/2Color Description
Pale GoldLens Color
Green
Color Code
004/69Color Description
GunmetalLens Color
Dark Violet
Color Code
004/2VColor Description
GunmetalLens Color
AzureLens Features
polarized
Frame Color
SilverColor Code
003/6DColor Description
SilverLens Color
Yellow Mirror Flash Gold
Frame Color
GoldColor Code
921387Color Description
Pale GoldLens Color
Dark Grey
Frame Color
SilverColor Code
003/6DColor Description
SilverLens Color
Yellow Mirror Flash Gold
Frame Color
GoldColor Code
921371Color Description
Pale GoldLens Color
Dark Green
Frame Color
SilverColor Code
003/80Color Description
SilverLens Color
Dark Blue
Frame Color
GoldColor Code
921371Color Description
Pale GoldLens Color
Dark Green
Frame Color
SilverColor Code
003/80Color Description
SilverLens Color
Dark Blue
Size Details
Size DetailsBridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5615-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
Bridge Width
15.00Temple Length
145.00Size
5915-145
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Frequently Asked Questions
Are the Ray-Ban Kai 3757 sunglasses prescription-ready?
Yes, the Ray-Ban Kai RB3757 sunglasses are fully prescription-ready. The metal frame and lens shape accommodate custom prescription lenses, including single vision and progressive options. Simply select your prescription details during checkout, and our licensed opticians will craft lenses to your exact specifications.
What does bio-based polyamide mean for the Kai 3757 lenses?
The Kai RB3757 features bio-based polyamide lenses with 40% bio-based carbon content derived from renewable sources like castor oil, tested according to ASTM D6866 standards. These lenses offer the same optical clarity, impact resistance, and 100% UV protection as traditional polyamide, but with a lower environmental footprint by replacing fossil-based materials with plant-derived alternatives.
What face shapes work best with the Ray-Ban Kai 3757?
The Ray-Ban Kai RB3757 is designed with a narrow, petite fit ideal for smaller face shapes. The oval frame shape is universally flattering and works well on heart, square, round, and oval faces. The adjustable nose pads allow for a customized fit, ensuring the frames sit comfortably without sliding.
Are polarized lenses available for the Kai 3757?
Yes, the Ray-Ban Kai RB3757 is available with polarized lenses in the Azure colorway (model 004/2V). Polarized lenses reduce glare from reflective surfaces like water, snow, and pavement, making them ideal for driving and outdoor activities. Non-polarized options are also available in green, dark violet, dark grey, and yellow mirror flash gold.
What sizes does the Ray-Ban Kai 3757 come in?
The Ray-Ban Kai RB3757 is available in two sizes: 56mm and 59mm lens width. Both sizes feature a 15mm bridge width and 145mm temple length. The 56mm size has a lens height of approximately 34mm, while the 59mm offers slightly more vertical coverage. Both are considered narrow/petite fits in Ray-Ban's sizing system.
How do I care for bio-based polyamide lenses?
Care for bio-based polyamide lenses the same way you would standard sunglasses: clean with a microfiber cloth and lens cleaner or mild soap and water. Avoid harsh chemicals, abrasive materials, and extreme heat. The bio-based material is durable and scratch-resistant, but proper care will extend the life of your lenses and maintain optical clarity.
Compare With Similar Frames
How the Ray-Ban Kai 3757 Sunglasses stacks up against the closest alternatives we carry.
- Iconic round shape with decades of heritage dating back to the 1960s
- Wider range of lens options including crystal glass
- Slightly larger fit options available (47mm, 50mm, 53mm)
- Distinctive hexagonal shape stands out more than oval
- Flat lenses create a unique modern look
- Similar slim metal construction and adjustable nose pads
Read the full comparison
Ray-Ban Kai 3757 vs Round Metal 3447 vs Hexagonal 3548N
Choosing between Ray-Ban's metal frame sunglasses often comes down to face shape, fit preference, and the vibe you're after. The Kai 3757 sits between the timeless Round Metal 3447 and the fashion-forward Hexagonal 3548N, offering a sweet spot of retro style and modern sustainability.
The Round Metal 3447 is Ray-Ban's heritage pick—a true icon that's been worn since the '60s. If you want a classic round shape with decades of proven style, the 3447 delivers. It's available in more lens materials, including crystal glass, and comes in a wider range of sizes. However, it lacks the Kai's bio-based materials and '90s-inspired edge. Round frames also tend to suit oval and square faces best, while the Kai's oval shape is more universally flattering.
The Hexagonal 3548N takes a bolder approach with its six-sided flat lenses and geometric silhouette. It's a statement piece that works well for fashion-conscious wearers who want something distinctive. The hexagonal shape is less versatile than the Kai's oval, and the flat lenses can create more glare compared to curved options. It's also priced higher and doesn't offer the sustainable bio-based lens technology.
The Kai 3757 stands out for its narrow fit (ideal for smaller faces), bio-based polyamide lenses with 40% renewable content, and color-contrast temple tips that add a modern twist. At $160–$197, it's competitively priced and offers a fresh take on oval frames without abandoning Ray-Ban's quality and heritage. If you're looking for a sustainable, retro-inspired frame that fits smaller faces and accepts prescription lenses, the Kai is your best bet.
At a Glance
Ray-Ban Round Metal 3447 Sunglasses
Pros:
- Iconic round shape with decades of heritage dating back to the 1960s
- Wider range of lens options including crystal glass
- Slightly larger fit options available (47mm, 50mm, 53mm)
- Classic design that never goes out of style
Cons:
- Round shape may not suit all face types as well as oval
- Does not feature bio-based sustainable materials
- Less modern aesthetic compared to the Kai's '90s-inspired design
- No color-contrast temple tips
Ray-Ban Hexagonal 3548N Sunglasses
Pros:
- Distinctive hexagonal shape stands out more than oval
- Flat lenses create a unique modern look
- Similar slim metal construction and adjustable nose pads
- Slightly larger fit works for medium face sizes
Cons:
- Hexagonal shape is less universally flattering than oval
- No bio-based lens options
- Flat lenses may cause more glare in certain conditions
- Higher price point ($143.50–$244)