A cutting insert includes a plurality of consecutively disposed, interlinked individual cutting inserts that can be brought into use successively through a respectively interposed predetermined breaking point by detaching a respectively preceding individual cutting insert in cutting use. The cutting insert has a blade-shaped construction with lower and upper bearing surfaces for being held in an elongated cutout with lower and upper opposing surfaces in a basic tool body of a grooving and cut-off tool or disk milling cutter. Each individual cutting insert is provided with a positioning device that cooperates with a complementary positioning device of the basic tool body. A grooving and cut-off tool or disk milling cutter and a wrench for the cutting insert, are also provided.