Well, it seems that you are not very familiar with UV protection on sunglasses. As a matter of fact, it means how capable the sunglasses could be in protecting your eyes against harmful lights. Maximum UV protection means that it could reflect almost all harmful lights and provide your eyes with the best protection. With that kind of sunglasses, you could enjoy a sunny day without fear.
Well, maximum UV protection on sunglasses means the great protection for the sunglasses from the UV rays. And it can be 100% UV protections. As we know that the sun emits three types of rays: visible, infrared and ultraviolet (UV). And you also should know that the invisible UV light is the component of sunlight most responsible for eye damage, so it is very important for sunglasses to provide UV protection. And most sunglasses offer UV protection which protects eyes against permanent sun damage and cataracts. But on the other hand, many sunglasses can only meet recommended standards for UV protection, offering about 60% UV protection. But you should know that sunglasses are also labeled with the words "max uv protection", that means it can protect your eyes from the largest UV rays. It can be 100% UV protection.
Most sunglasses offer UV protection that protects eyes against permanent sun damage and cataracts. Sunglasses that meet recommended standards for UV protection offer at least 60% UVA protection and at least 70% UVB protection. Some sunglasses labels may say "UV absorption up to 400nm," which is equivalent to 100% UV protection. The maximum uv protection on sunglasses means the protection index from the uv which will protect your eyes. Usually you get the sunglasses with the above standard is OK. If you are out, you'd better choose the pair of sunglasses to make your eyes shield from the strong sun lights. In addition, you could buy the sunglasses to improve the whole beauty in the look.