MS21209F420L - Screw Threaded Insert by Helicoil Stanley Engineered Fastening

The Heli-Coil MS21209F420L is a military-standard screw-locking wire thread insert engineered to create high-strength, permanent internal threads in light metals, structural alloys, and composite materials. Precision-formed from cold-drawn 304 stainless steel wire with a specialized diamond cross-section, this tanged insert features an internal locking coil with straight, resilient chordal segments. As a mating male bolt enters, these flat segments flex outward, exerting a continuous, controlled prevailing torque that grips the fastener securely. This configuration delivers robust vibration resistance, preventing rotational loosening under harsh dynamic stress while shielding delicate parent materials from internal thread stripping, fatigue, and galling.

Internal Screw-Locking Profile Deformed chordal coils apply continuous prevailing locking torque to secure mating hardware tightly against severe operational shock and vibration.

Standard Driving Tang Engineered with an integrated drive tang on the leading coil for positive tool engagement and fast, precise insertion depth setting.

Austenitic Stainless Steel Construction Crafted from work-hardened corrosion-resistant steel to establish a wear-proof thread foundation that protects soft host materials from stripping.

Dry Film Lubricant Finish Pre-coated with a specialized dry film lubricant to stabilize installation torque, ensure uniform clamping force, and eliminate friction galling.