Drill chuck holder made of alloyed tool steel. Hardened to 58 ± 2 HRC, with a minimum depth of 0.5 mm. Tensile strength in the core after case hardening is approximately 950 N/mm². Taper according to DIN 254 with a taper angle tolerance of AT3. Surface accuracy of the taper Ra < 1 µm. Runout accuracy ≤ 0.01 mm. Balancing quality G 6.3 at 15000 min-1. Tool holder ISO 7388-2 (JIS B 6339 MAS/BT). Designed for holding three-jaw chucks with internal taper according to DIN 238.