The thickest acetate around.  Factory 900 features a proprietary hinge mechanism making these frames especially comfortable.  They describe themselves as:

FACTORY900 was launched in 2000 as a house-brand of AOYAMA Optical Ltd. Co.
"900" is derived from the number designated to our factory by the government.

We, at AOYAMA Optical, are a small factory and have been manufacturing plastic frames for three generations over the last 80 years in Fukui where 95% of "made in Japan" eyewear frames are manufactured. During AOYAMA Optical's history, we have always challenged ourselves until obtaining magnificent plastic frame-forming techniques. In 2000, a head designer, Mr. Yoshinori Aoyama and we started our own house brand with the brand concept "THE FUTURES EYEWEAR" to create more sophisticated and exquisite eyewear. Thus, FACTORY900 can deal with all process of producing eyewear from a design to manufacturing. 

Unique shapes and avant-garde designs have gained great reputation worldwide.
We received the Japanese Eyewear Award - "Eyewear of the Year" - three years in a row in 2002, 2003 and 2004. We also received the "Slimo d'Or" of Paris, France, in 2013 and 2015. (The Silmo d'Or is considered to be the Academy Award of the eyewear field.)

With our great artisans' techniques, each unit of "THE FUTURE EYEWEAR" frames is finished individually with great care. This revolutionary product has come to the world.....

under the name "FACTORY900".