Walfront 200Pcs M3 Flat Countersunk head Socket Screw Machine Fastener Assortment Kit with Storage Box, 4/6/8/10/12/16/20/25mm

Premium Grade 10.9 Alloy Steel: Crafted with aerospace-grade alloy steel hardened to 10.9 rating, these screws withstand 1000+ N/mm² tensile strength 30% stronger than standard fasteners. Black oxide coating provides saltwater corrosion resistance, passing 500hrs salt spray testing for marine use. Precision Countersunk Design: Laser-engraved Torx TR20 drive ensures 6x better transfer than Phillips heads. 90° flat head seating creates seamless alignment (±0.1mm tolerance), perfect for CNC machining and electronics enclosures. 15 Sizes for Versatile Applications: From 4mm mini screws for PCB mounting to 25mm heavy-duty fasteners, this 200pc kit covers 90% of M3 applications. Includes 5 size groupings with color-coded compartments. Marine-Grade Zinc-nickel plating combined with dichromate passivation creates triple-layer defense against humidity. Tested to withstand 95% RH environments for 12 months without oxidation - ideal for boat engines and outdoor electronics. Professional Organization System: Military-grade PP case with shockproof foam insert keeps screws dust-free. Each compartment has engraved size labels and quantity indicators (40pcs/size average). Carry handle and IP54 rating make it jobsite-ready.