Bulk #4-40 Phillips Flat-Undercut Thread-Cutting Screws — Type F, Bright-Zinc Steel ISO 4035 Improved Tuning Stability: Locking nuts

Improved Tuning Stability: Locking nuts clamp strings in place to prevent slippage

meeting SAE’s highest grade specifications

Head Style: Pan head provides wide contact and low-profile appearance

Q: What materials are these hex keys made from

Head / Drive: Unslotted indent hex-washer (5⁄16″ A/F) — smooth top forge

Bulk #4-40 Phillips Flat-Undercut Thread-Cutting Screws — Type F, Bright-Zinc Steel ISO 4035 Improved Tuning Stability: Locking nutsMonster Overview: When standard countersinks are too shallow or sheet metal is wafer thin, choose #4 40 Phillips Flat Undercut Thread Cutting Screws. The undercut head trims most of the 82 cone, giving you maximum thread engagement while finishing perfectly flush in sheet as thin as 0. 040. Heat treated carbon steel sports a brilliant bright zinc electro plate, is hydrogen relief baked to banish embrittlement, and topped with a factory dry wax film