Zero Clearance inserts reduce splintering, chipout, splinters that can get lodged in the opening and, as a result of the small (blade width) opening, dust generation is minimal. Zero clearance inserts are especially important when cutting thin plastic or laminate so you can avoid the material chipping or cracking because the bottom of the material is supported, resulting in a more precise and safe cut. Made of Double-sided Laminated High Density Phenolic (DLHDP) which is extra hard and stiff. Material slides across it like glass. Colors may vary.