We've been doing this since 2007.
At first, we existed simply as an Original Design Manufacturer (ODM). We helped eyewear companies design and produce eyewear retainers to prevent their eyeglasses from slipping.
After some testing, we quickly realized that it was impossible to design one style of retainer to fit all types of eyewear.
There was simply too much (head, eyeglass, and environment*) variation from one person to another to accomodate just one eyewear retainer style.
But of all the variations we analyzed, two in particular deserve mentioning: eyeglass temple tip and temple bend width.
Incidentally, "temple" in this context = the arms of your eyeglasses.
Now then, when you put on a pair of Keepons, you have to stretch the opening (the hole) over your eyeglass temple tip (usually the widest part of your temples) and move it to where your eyeglass temple starts to bend (usually the narrowest part). At which point, the opening narrows, and hopefully the hole is small enough to sit snugly in place, to do its job.
Point is, if the hole is too small, you won't get it on your glasses. If the hole is too big, it won't sit snugly in place.
This in itself indeed poses some engineering difficulties, but these difficulties are greatly increased when we consider that some eyewear styles (like Ray-Ban Aviators for example) come with really wide temple tips and really narrow temple bends.
From a design perspective, one solution would be to design all Keepons with a really small hole and make them out of pure silicone so the holes can stretch really wide (like those silicone workout bands).
But from an engineering perspective, pure silicone is too soft and flimsy, such that in use the Keepons wouldn't be able to hook over your ears firmly enough, or take hold of your glasses tightly enough. Or would simply rip with extended use.
Naturally, other polymers are added to create a blend which is resilient and not too soft and not too hard. But at the end of the day, we're still faced with the problem that a small hole can only stretch so wide.
And it's because of this fact, that we can't just make a single Keepons style that fits all types of eyeglasses.
In light of this, eyeglass companies began commissioning us to develop a single eyewear retainer style to match their single best-selling eyeglass style. One for one.
For example, for one Japanese eyewear retailer chain whose best selling product were Ray-Ban Wayfarers, we designed and produced for them what is now our Keepons Superstretch Black.
One by one, every Keepons style was made as a commission for different eyeglass companies who approached us with different requirements.
Make them for this pair of frames please!
A longer hook please!
A fatter body please!
It went on like this, and when our ODM agreements with them expired, those designs were then marketed under our own Keepons brand.
Fast forward to today, we're Keepons the company and the brand, and we're the world's largest maker of elastomer eyewear retainers. And our motto, we have two actually: "Keepons keep your glasses on", and "Keepons, the science of stopping slipping glasses" speaks to the fact that our sole purpose for being is to continually pursue the goal of stopping all the world's eyeglasses from slipping.
*head specific variations (nose bridge height, nose to ear distance, ear shape, perspiration tendencies, etc.), eyeglass specific variations (lens and frame weight, temple material, temple length, temple tip width, temple bend width, temple bend angle, etc.), and environment-specific variations (climate, activity levels, etc.)