When sourcing hex shank drills, the most critical factor is the material composition. For general metalworking, HSS (High-Speed Steel) is standard, but for stainless steel or hard alloys, HSS-Co (Cobalt) is required. The shank size is typically 1/4-inch (6.35mm), which must adhere to DIN 3126-E6.3 standards to ensure compatibility with quick-change chucks and impact drivers. Additionally, look for a 135-degree split point to prevent 'walking' and ensure self-centering during high-speed operations.