HELIFOUNER 3/8-16 x 20mm Wood Threaded Inserts, 20 Pieces

Pieces: HELIFOUNER wood threaded inserts are a 20-piece set with 3/8-16 internal threads and a stated 20mm length. The zinc-finished carbon steel inserts are driven through an internal hex, with the listing describing use in wood and composite materials.

At a glance

Designed for screw-in installation into drilled wood holes using an internal hex drive.
The listing describes use in soft wood, plywood, fiberboard and composite materials, as well as furniture repair.
A 15mm drill bit is specified for the pilot hole, with a countersink to the insert head size.

Price

$6.49Save 50%

Reference price: ~~$12.99~~

Price checked: Nov 12, 2026

View offer Ahead of Black FridayExplore the selection

Often bought together

8 Pack 5/16-18 x 3 Inch Hanger Bolts Double Headed Bolts Self-Tapping Screw Inch Hanger Bolts for Furniture

$8.99

Milescraft 1219 Circle Guide Kit- Precision Router Circle Cutting Jig For Cutting/Routing Circles From 1.5” Up To 52” with Offset Base

$49.99

Pros and cons

Pros

The 3/8"-16 internal thread suits projects using that stated coarse thread size.
The internal hex drive and listed 20mm insert length support screw-in installation in furniture and woodworking projects.
The listing claims zinc-plated carbon steel construction and includes a hex wrench in its package description.

Technical specifications

14 specifications

Identity and set
Brand	HELIFOUNER
Model	HELIFOUNER-Nut-Inserts
Set quantity	20

Materials and finish
Material listed	Carbon Steel
Exterior finish	Zinc

Thread and dimensions
Thread size	3/8"-16
Thread type	Unified National Coarse
Thread coverage	Fully Threaded
Thread class	Coarse
Size name	3/8"-16 x 20mm
Item diameter	15 millimeters
Outside diameter	0.38 inches
Compatible groove diameter	0.59 inches

Drive
Drive style	Internal Hex

What to know before buying

Listing details to confirm

Listing details are inconsistent about compatible bolts: the title and specifications state 3/8-16, while installation text also says 5/16-18. The stated 15mm pilot-hole size, 0.38-inch outside diameter and 0.59-inch compatible groove diameter do not align clearly. Confirm the correct screw thread and hole dimensions for the selected listing before installation.

Who is it for?

A good fit for

Wood furniture repairs such as chair legs, cabinets, headboards and footboards, where a 3/8-16 threaded insert is the intended fit.
Woodworkers seeking a set of 20 inserts for soft wood, plywood or composite materials.

Less suited to

Projects needing a confirmed screw size or hole dimension without first resolving the listing's inconsistent fit details.
Applications requiring a different insert thread size or a verified material-performance rating.

HELIFOUNER 3/8-16 x 20mm Wood Threaded Inserts, 20 Pieces · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.6 / 5 · 306 ratings

5 stars75%75%
4 stars18%18%
3 stars6%6%
2 stars1%1%
1 star0%0%

Aggregate ratings lean positive, with most ratings in the top two star categories, but they do not reveal specific strengths, complaints or reasons for satisfaction. For a furniture repair, verify the screw thread and hole dimensions first, since the listing gives inconsistent fit guidance.

Frequently asked questions

What size thread do these inserts use?

The listed thread size is 3/8"-16, described as Unified National Coarse. However, installation text also mentions 5/16-18 bolts, so confirm the intended screw compatibility before buying.

What hole size does the listing recommend?

It specifies a 15mm drill bit and separately gives a 0.59-inch compatible groove diameter. Those details are not clearly consistent, so verify the required hole size for the selected insert.

What materials are these inserts intended for?

The listing describes applications in soft wood, plywood, fiberboard and composite materials, including furniture repairs.

Is a wrench included?

The package description claims one 8mm hex wrench is included. Check the selected listing because its package details are not independently confirmed.