X-Acto - No. 28 Concave Carving Blade - 5 Pack - X-Acto No. 28 Concave Carving Knife Blade are great for whittling and curved shaping. Xacto Number 28 Carving Blades cut balsa, leather, linoleum, and plastic with ease. These Blades have a Concave Edge. Fits 3/8 inch X-ACTO No 2, Type c, and Type D handles, as well as Excel K2, K5, K6, and K7 Handles. This is the replacement for X-ACTO X28, which has been discontinued by X-ACTO. Includes 5 Blades.