Park Tool SAC-2 is specifically formulated to help prevent slipping on bicycle seatposts, handlebars, and stems. SAC-2 creates friction between surfaces for an extra-secure grip, while also forming a protective barrier between different materials. Ideal for carbon fiber, aluminum, and steel. NOTESAC-2 contains small bits of hard silica. This silica may cause minor cosmetic blemishing on finished surfaces. Do not use SAC-2 on threaded parts or for bearing lubrication.