Choosing the right 4-40 UNC hex head screws and matching hardware helps ensure durable, corrosion-resistant assemblies for projects in electronics, cabinetry, automotive, and DIY repairs. This guide reviews top stainless steel kits that include hex head screws, nuts, and washers, all sized #4-40 with full threads. Each option emphasizes complete assortments, reliable 304 stainless steel quality, and convenient packaging for quick selection on the job.
| Product | Brand | Pieces | Includes |
|---|---|---|---|
| MCMASKE 280PCS | MCMASKE | 280 | Hex socket head cap screws, nuts, flat washers |
| HELIFOUNER 250PCS | HELIFOUNER | 250 | Hex bolts, nuts, washers |
| Guard4U 280Pcs | Guard4U | 280 | Hex socket head cap screws, nuts |
| MCMASKE 260PCS | MCMASKE | 260 | Hex machine screws, nuts |
| HELIFOUNER 240 Pieces | HELIFOUNER | 240 | Phillips pan head machine screws, nuts |
MCMASKE 280Pcs #4-40 UNC Stainless Steel Kit
Product overview and fit: This assortment emphasizes coarse-thread #4-40 screws with full thread, provided in multiple lengths to accommodate various projects. The kit includes 304 stainless steel screws, matching hex nuts (50 pieces) and flat washers (50 pieces). All screws are designed for chemical resistance and reliable corrosion resistance in standard environments. Lengths range from 3/16″ to 1″ and are measured from under the head, offering compatibility with typical electronics, enclosures, and light mechanical builds.
Key considerations
Materials: 304 stainless steel provides corrosion resistance and moderate magnetic properties, making them suitable for damp or mildly acidic environments. Threading: right-hand, coarse thread (34-40 TPI) is standard for general assembly. Packaging: organized pieces help minimize search time on quick-turn jobs.
HELIFOUNER 250Pcs #4-40 Hex Bolts Kit
Kit composition and dimensions: Includes eight size variations from 3/16″ to 1″ with hex nuts and flat washers, all in a durable transparent box for quick size identification. Made from 304 stainless steel with good corrosion resistance in challenging conditions such as high heat, humidity, or outdoor environments. The set is designed for multiple needs, from small mechanical assemblies to electronics enclosures requiring fasteners of consistent quality.
Key considerations
Versatility: A broad range of lengths allows precise tightening and load distribution. Convenience: Neatly labeled packaging reduces mix-ups on the job site. Quality: 304 stainless steel ensures long-term durability against rust and oxidation in common environments.
Guard4U 280Pcs #4-40 UNC Kit
Contents and standards: This kit assembles high-precision #4-40 UNC hex socket head cap screws with nuts, meeting ANSI B18.3 specifications. The 304 stainless steel construction provides corrosion resistance, while the various lengths—from 3/16″ through 1″—accommodate both compact and extended fastening needs. Each length includes a balanced count (20 pieces per length) and 100 nuts to pair with the screws, supporting flexible project configurations.
Key considerations
Standards compliance: Alignment with ANSI specifications helps ensure compatibility with existing hardware. Corrosion resistance: Stainless steel maintains performance in moisture-prone or slightly corrosive settings. Organization: Clear distribution of lengths aids quick assembly during fieldwork.
MCMASKE 260PCS #4-40 UNC Stainless Steel Phillips
Focus on machine screws and nuts: This set provides 260 pieces of #4-40 UNC stainless steel Phillips flat-head machine screws, designed with standard bevel under the head. The screws are fully threaded and include matching hex nuts (80 pieces) to complete assemblies with strong, uniform torque. Lengths span multiple common needs, ensuring compatibility with electronics housings, brackets, and small mechanical frames.
Key considerations
Head style and compatibility: Phillips flat-head screws are suitable for countersunk applications or where flush mounting is required. Material on-hand: 304 stainless steel supports rust resistance and structural integrity in typical workshop environments. Quantity balance: Sufficient nuts ensure you can fasten without hunting for matching pieces mid-project.
MCMASKE 290PCS #4-40 UNC Phillips Pan Head Kit
Overview and content: This set features 290 pieces of #4-40 UNC Phillips pan head machine screws with matching nuts and flat washers. Made from 304 stainless steel, these screws offer chemical resistance and durability, with coarse threading suitable for general-purpose fastening. The kit emphasizes a wide range of lengths to cover multiple assembly scenarios, especially where a pan head is preferred for ease of drive and load distribution.
Key considerations
Drive type: Pan heads offer better load distribution and countersinking options on certain assemblies. Corrosion resistance: 304 stainless steel remains a reliable choice for varied environments. Complete kit: Included washers and nuts help speed up assembly without separate shopping for hardware.
HVAZI 260PCS #4-40 UNC Stainless Steel Kit
The HVAZI assortment highlights a comprehensive 260-piece collection of #4-40 UNC hex socket head cap screws with hex nuts. The kit uses 304 stainless steel with full thread, in lengths ranging from 3/16″ to 1″, and includes 80 hex nuts. The product is designed for precision fastening in automotive, electronics, and small machinery where a robust fastener is essential and where form-fitting head profiles matter for tight spaces.
Key considerations
Thread type and length: Coarse threads and full-thread design provide consistent engagement across multiple materials. Quick identification: A varied length set helps you choose the exact grip and thread length for each task. Material reliability: 304 stainless steel supports long-term performance in diverse conditions.
iexcell 100Pcs #4-40 Hex Socket Button Head Kit
Specialty features and contents: This kit includes 100 pieces of #4-40 x 1/4″ hex socket button head screws, plus one hex key for convenient drive. The screws are 304 stainless steel with a compact total length plus a low-profile button head ideal for applications requiring minimal protrusion. A hex key included aids quick setup without additional tools. The finish provides anti-corrosion properties for varied environments.
Key considerations
Head style and accessibility: Button heads are useful where space is tight or a low-profile head is needed. Included tool: The hex key simplifies installation in portable or recessed applications. Material and durability: Stainless steel 304 offers corrosion resistance and adequate strength for modest loads.
Buying Guide: Key Purchase Considerations And Comparisons
Fastener quality: Look for sets that specify 304 stainless steel for corrosion resistance and long-term durability. Verify the thread pitch (40 per inch) and the diameter (#4) to ensure compatibility with existing nuts and threaded holes. Head style: Choose hex socket head caps for stronger torque and flush mounting in tight spaces; pan head or button head options suit different surface profiles and clearance requirements. Full-thread length is often preferred for reliable clamping force and better grip in softer materials.
Completeness and packaging: Kits that include matching nuts and flat washers save time because you don’t need separate purchases. A labeled, organized storage box helps you locate the correct length quickly, which is essential during on-site repairs or complex assemblies. Length variety (from 3/16″ to 1″) increases adaptability for electronics housings, control panels, and brackets.
Application scope: For electronics, cabinets, automotive trim, and light machinery, these 4-40 UNC fasteners are common due to their small size and robust stainless construction. Consider the environment: damp or outdoor settings benefit from stainless steel, while benign indoor settings may tolerate plated alternatives. Availability of a range of sizes in a single kit reduces the need for frequent reordering and helps standardize fasteners across projects.
Quality control and standards: Prefer kits that adhere to recognized standards and include sufficient quantities of nuts and washers to avoid mismatches. If you anticipate frequent use, a larger kit with a wide length range offers greater versatility and reduces downtime.
Maintenance and care: Stainless fasteners resist rust but should be kept dry and free of contaminants to maximize lifespan. Store them in their original packaging or a labeled organizer to prevent mixing sizes and ensure consistent torque during assembly.