E-z Lok 303-004 Thread Locking Insert 4-40 X 10-32 Unc

Product Description

The E-Z LOK 303-004 is a self-locking threaded insert designed to create a secure, vibration-resistant internal thread in a parent material that accepts a 10-32 external thread. The insert installs using a standard tap and provides a 4-40 internal thread for the fastener. Manufactured from 303-grade stainless steel with a bright finish, it delivers corrosion resistance and high tensile strength in demanding service environments. At 0.25 inches overall length, it is compact enough for use in thin-wall and close-tolerance assemblies. Rated tensile strength is 1,198 pounds. The 2B internal and 2A external thread class of fit meets standard UNC tolerance requirements.

This insert is used in applications where a threaded hole must be locked against rotation or pull-out, including light mechanical assemblies, electronic enclosures, instrument panels, and precision fabricated components. It is suitable for installation in metal, plastic, or composite base materials where a permanent, load-bearing thread anchor is required. The self-locking wall design generates interference with the parent material to resist loosening under vibration or cyclic loading. Installers working in HVAC controls, electrical panel fabrication, and instrumentation assembly will find this insert useful where small-diameter fasteners must be reliably retained.

Key Features

• 4-40 internal thread with 2B class of fit for standard fastener engagement
• 10-32 external thread with 2A class of fit for installation into parent material
• Self-locking wall design resists loosening under vibration and cyclic loads
• 303 stainless steel construction with bright finish for corrosion resistance
• 1,198 pounds rated tensile strength
• 0.25 inch overall length suits thin-wall and compact assemblies
• Compatible with standard tap installation - no special tooling required

Compatibility

Designed as an OEM-style replacement or new-installation threaded insert for any application requiring a 4-40 internal thread anchored by a 10-32 external thread in UNC standard.

Installation Notes

Installation is performed with a standard tap tool sized for the 10-32 external thread; consult the tap drill chart for the correct parent-material hole size before installation. Ensure the parent material bore is clean and free of debris before driving the insert. For threaded assemblies in electrical or control panel applications, follow applicable NEC guidelines for hardware torque and fastener retention. Do not over-drive the insert, as deformation of the locking wall can reduce thread integrity.