20zy M3 M4 Black 8.8 High Strength Countersunk Head Hex Self Tapping Screw Bk Bolt Flat Head Tapping Screw

20zy M3 M4 Black 8.8 High Strength Countersunk Head Hex Self Tapping Screw Bk Bolt Flat Head Tapping Screw. Corrosion Resistant Coating: Black phosphate coating provides enhanced durability and low-reflective matte finish. Easy Installation Design: Sharp point penetrates drywall and metal studs without pre-drilling, saving time. Flush Finish Capability: Bugle head countersinks smoothly without tearing paper for seamless joint application. Superior Holding Power: Fine threads reduce loosening risk in drywall and metal studs over time. Customizable Surface: Surface treatment options include Black/Gray Phosphated and Yellow Zinc. Flexible Length Options: Available in lengths ranging from 16mm to 60mm to suit various needs. Dual-Thread Technology: Optional upper threads grip wood studs while lower threads secure drywall. Factory Direct Supply: Direct from manufacturer with strict quality control and 10+ years expertise.