Space-Age Ceramics Help Blades Run Cool, Lasts Longer. I would never have guessed that ceramics would make effective band saw guide blocks. Yet because the ceramic used is inherently slick, extremely hard, and incredibly durable, your blades will last longer, track truer, and run smoother Used for over 15 years in the sawmill industry (where changing a blade is a major operation), they have just recently been fabricated in sizes suitable for use on the 14"and 16" saws popular with cabinet shops and recreational woodworkers. Suitable for use with all blade widths. (4) Measure 5/16 x 5/16 x 3/4. Made in the USA.