• Men's glasses frames with FL41 lenses
•  
• Option A: Dark lens, 72% indoor blocking.Photochromic, becomes sunglasses outside.
• Option B: Light tint lens, 40% directional blocking & 73% high transmittance. For moderate photophobia & color-sensitive users. Indoor use only, no photochromism.

1. Why 480–520nm Light Irritates Eyes
Human eyes have rods (night vision) and cones (color & detail).
In early 2000s, scientists found ipRGCs, a third light-sensing cell. It carries melanopsin, highly sensitive
to 480–520nm cyan-green light. Too much light in this band triggers glare and eye discomfort from LEDs,
fluorescent lights and sunlight.

2. Where FL41 Comes From

FL41 stands for Fluorescent Light Formula 41, created in late 1980s by Professor Arnold Wilkins in Birmingham,
UK. Old office fluorescent lights flicker invisibly with strong 480–520nm spectrum, causing eye strain for
workers. After many trials, his 41st rose-tint lens formula perfectly filters harsh fluorescent light, named FL-41.

3. How FL41 Lenses Work

Originally made for office eye fatigue relief.
FL41 rose lenses block irritating 480–520nm cyan-green light and cut glare from screens, lamps and sun.
Different from dark sunglasses, it stays transparent indoors without dim vision, also softens harsh outdoor
light for office, study and daily outdoor use.

 SHINU FL41A DARK LENS TEST DATE

SHINU FL41B light lens test date

please check the size before your order. this is very important.

C1   black

                                            C2 outside black inside clear

 c4. DEMI BROWN

c20 MATTE BLACK