HELIFOUNER #4-40 Nylon Insert Hex Lock Nuts, 50-Piece Set

HELIFOUNER #4-40 nylon insert hex lock nuts are a 50-piece set made for matching coarse-thread fasteners. The listing specifies 304 stainless steel and describes a nylon collar intended to reduce loosening from vibration and torque.

At a glance

Nylon insert collar is described as helping resist loosening under vibration and torque.
Coarse #4-40 thread, fully threaded body and external hex drive.
Listing identifies the nuts as 304 stainless steel and silver-colored.

Price

$3.49Save 50%

Reference price: ~~$6.99~~

Price checked: Nov 12, 2026

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Pros and cons

Pros

A 50-piece quantity suits small assemblies and repair work using the specified thread size.
Nylon insert design provides a locking feature without requiring a separate locking washer, according to the listing.
Stainless-steel construction is specified for applications where corrosion resistance is a consideration.

Technical specifications

16 specifications

Identity
Brand	HELIFOUNER
Model	HELIFOUNER-lock-nuts

Thread and design
Thread size	#4-40
Thread type	Fully Threaded
Thread style	Right Hand
Thread class	Coarse
Hex style	Hexagonal
Drive style	External Hex
Compatible groove diameter	0.16 inches
Fastener type	Lock

Materials and finish
Material listed	Stainless Steel
Grade rating	304 Stainless Steel
Color	Silver
Finish type	Polished

Pack and weight
Number of pieces	50
Weight listed	0.04 kg

What to know before buying

Listing details to confirm

Confirm that #4-40 coarse threads match the mating bolt. The listing describes 50 nuts packed in a plastic case, while its package-included description names only the nuts, so whether a case is included is unclear. The stated corrosion and vibration performance are manufacturer claims, not independently verified.

Who is it for?

A good fit for

Small repairs and assemblies using compatible #4-40 coarse-thread bolts.
Buyers seeking nylon-insert locking nuts in a 50-piece quantity.

Less suited to

Projects requiring a thread size other than #4-40 or a non-coarse thread.

HELIFOUNER #4-40 Nylon Insert Hex Lock Nuts, 50-Piece Set · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.5 / 5 · 87 ratings

5 stars75%75%
4 stars14%14%
3 stars5%5%
2 stars2%2%
1 star4%4%

Aggregate ratings lean positive, with most ratings in the five-star category, but a smaller share falls in lower categories. No written customer feedback is supplied, so the ratings do not establish why buyers were satisfied or dissatisfied. For a small fastener set, buyers should judge fit against the specified #4-40 thread rather than infer performance from the overall rating.

Frequently asked questions

What thread size are these nuts?

The listing specifies #4-40 coarse thread. Match the size and pitch to the bolt before ordering.

How many nuts are included?

The listing states a quantity of 50. It describes a plastic case in one feature, but the package-included wording lists the nuts alone, so case inclusion is uncertain.

What does the nylon insert do?

The listing says the collar is intended to reduce loosening under vibration and torque. It does not provide independent performance testing.

What material is listed?

The product details list stainless steel, and the title and description specify 304 stainless steel.