X-ACTO X239 Extra Fine Razor Saw Blade. For Delicate Sawing in Confined Areas. Balsa wood, fiberglass, plastic, and railroad tracks. 5 1/2 inch Long x 1 1/4 inch Deep, 52 teeth per inch, 0.012 inch Thick Extra Fine Saw Blade. Carbon steel blade for a reliable cut every time Attaining this level of precision, accuracy and reliability starts with supreme quality craftsmanship The original X-ACTO knife/blade has been praised for more than 50 years as the standard for precision.