High-performance tool system with 12 cutting edges for groove and slot milling with milling depths up to 16.5 mm! The system consists of carbide and steel toolhoders with internal coolant supply and milling inserts with 12 cutting edges with cutting widths from 0.5 mm and up to 6.0 mm. Thanks to high-performance toothing technology from Kaestner-Tools, torsion at the insert-holder interface is effectively counteracted and the insert sits very stably in the insert seat. This results in high torques and feeds are possible, a higher cutting performance is achieved and ultimately main times are reduced. Milling inserts: The milling inserts are available in cutting widths between 0.5 mm and 6.0 mm and are subdivided as follows: Cutting widths 0.5 mm /1.0 mm: well-proven cutting edge geometry for a wide range of applications, without corner radii Cutting widths 1.5 mm / 2.0 mm / 2.5 mm / 3.0 mm: GY geometry with staggered teeth with bilateral corner radii for smooth cuts and high surface qualities Cutting widths 4.0 mm / 5.0 mm / 6.0 mm: GY geometry with staggered teeth, a single-sided corner radius and an additional 45° chamfer for a division of the cut and thus less cutting pressure Tool holders: Carbide: With internal coolant supply, with shank diameter 16.0 mm and with usable lengths of 60.0 mm / 90.0 mm / 120.0 mm. Shank according to DIN 6535 HA. Steel: With internal coolant supply, with shank diameter 20.0 mm and a usable length of 32.0 mm. Shank according to DIN 1835 A.