Fuji's engineers thought long and hard on how to make a guide lighter and stronger yet keep the cost down. After years of research they came up with Alconite®, a special type of ceramic that offers strength, lightness, and durability. In fact Alconite® offers 80% greater compression strength and is 20% lighter than Aluminum Oxide. Also, through Fuji's Diamond Polishing, Alconite® boasts one of the smoothest finishes in guide rings. Fuji engineers have made Alconite® one of the thinnest and lightest ceramic rings available today! When combined with the lightweight Concept K-Series™ Tangle Free frames the results are unparalleled ... 35% lighter and up to 50% stronger than ordinary guides.