These are great retainers. They fit my rayban's and my husband's electric's, and they're very light weight.
Just purchased the Tech cord eyeglass retainer, and am very pleased with the product. I have white hair and was looking for something that blended in and did not distract when wearing earrings or necklace. This product is visually perfect for that. It is also soft, very flexible and comfortable around the neck and face. The slides which attach the cord to my glasses are secure, and not so bulky that I feel pressure on my temples. I'm very pleased with these keepers, and will probably purchase them again, if needed. Might try some colors for fun. (Lavender would be nice, if it were available.)