# 12 -14 with #3 Drill Point Phillips Undercut Flat Head Elco Dril-Flex
Dril-Flex fasteners are specially designed and processed to help prevent hydrogen-induced brittle failures. Each fastener undergoes a unique dual-hardening process to ensure the optimal combination of ductility and hardness required for maximum performance in the field. Dril-Flex fasteners offer a unique dual-hardening process. The self-drilling point and lead tapping threads are selectively hardened to a minimum of HRC 52. The load-bearing portion of the screw is held at or below the critical HRC 34 level. This reduced hardness level also meets SAE J429 Grade 5 and ASTM A449 strength and ductility standards.