Electro Hardware P553M10F21-440 Female Standoff 4-40

Product Description

The ELECTRO HARDWARE P553M10F21-440 is a round female standoff designed for use in precision fastening applications where consistent spacing and thread engagement are critical. This fully threaded standoff features a 4-40 thread size, an overall length of 0.875 inches, and an outside diameter of 0.25 inches. Constructed from Grade 2 steel with a zinc-plated finish, it meets ASTM B633 Type 1 and QQ-S-633 standards for corrosion resistance. The fully threaded interior accommodates a thread depth of 1 inch, providing reliable thread engagement across a range of panel thicknesses. Electricians, electronics assemblers, and panel fabricators commonly use this type of standoff in control panels, enclosures, and circuit board mounting assemblies.

This standoff is suited for light-duty to medium-duty panel and PCB mounting tasks in electrical enclosures, control cabinets, and equipment chassis. The inch-system dimensions make it compatible with standard 4-40 fastener hardware widely used in domestic electrical and electronics assembly work. Its compact 0.25-inch outside diameter fits applications where space between mounting points is limited. The zinc-plated finish provides surface protection appropriate for indoor and sheltered environments.

Key Features

• Fully threaded female interior with 4-40 thread size for standard fastener compatibility
• 0.875-inch overall length with a length tolerance of -0.005 to 0.005 inches for precision fitment
• 0.25-inch outside diameter suits tight-clearance panel and PCB mounting applications
• Grade 2 steel construction provides reliable mechanical strength for general fastening use
• Zinc-plated finish meets ASTM B633 Type 1 and QQ-S-633 corrosion-resistance standards
• Round body shape allows installation with standard hex or knurled drivers

Compatibility

Designed as a standard-dimension replacement or new-install female standoff for applications using 4-40 inch-series threaded hardware in electrical enclosures, control panels, and electronics chassis assemblies.

Installation Notes

Install and remove female standoffs using appropriately sized drivers or nut drivers to avoid deforming the body or cross-threading the interior. Always de-energize and lock out the equipment before working inside control panels or enclosures per applicable NFPA 70 lockout-tagout procedures. Do not overtighten mating fasteners, as the 4-40 thread is a fine, small-diameter thread susceptible to stripping under excessive torque. Inspect threads before installation to confirm they are clean and free of debris.