---
title: "What Are Magnetic Bit Holders and Extensions Used For?"
description: "Magnetic Bit Holders and Extensions (DIN 3126 / ISO 1173 (C6.3 hexagon drive)) are used for installing, adjusting or servicing the assembly rather than formi…"
url: https://engineeringhardware.com/applications/magnetic-bit-holders/
source: Engineering Hardware & Fasteners
---

# What Are Magnetic Bit Holders and Extensions Used For?

Tools · DIN 3126 / ISO 1173 (C6.3 hexagon drive) · Application guide

Typical applications, the industries that specify magnetic bit holders and extensions, and how to choose the right size, material and finish for the joint.

Magnetic Bit Holders and Extensions are used for installing, adjusting or servicing the assembly rather than forming part of it. They are manufactured to DIN 3126 / ISO 1173 (C6.3 hexagon drive), and selection is driven by the size designation, the fit and tolerance the assembly requires, and the service environment.

- **Primary duty:** Installing, adjusting or servicing the assembly rather than forming part of it
- **Governing standard:** DIN 3126 / ISO 1173 (C6.3 hexagon drive)
- **Category:** Tools

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

![What Are Magnetic Bit Holders and Extensions Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/09/Magnetic-Bit-Holders.webp)

Magnetic Bit Holders and Extensions (DIN 3126 / ISO 1173 (C6.3 hexagon drive)) are specified where the joint requires installing, adjusting or servicing the assembly rather than forming part of it. The sections below cover the typical end-uses by industry, the size and material decisions for each, assembly practice, and the applications this fastener type is not suited to.

## Typical Applications for Magnetic Bit Holders and Extensions

The most common settings where these are specified:

- **General machine building:** fastening covers, brackets, motors and sub-assemblies on production equipment.
- **Maintenance & repair (MRO):** a stocked size for servicing existing plant where the original fastener spec must be matched.
- **Fabrication & metalwork:** bench and on-site assembly of steel frames, enclosures and weldments.

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## How to Specify Magnetic Bit Holders and Extensions for Your Application

- **Size:** Match the size to the mating part — see the dimension table below for each option.
- **Material:** Choose the material and finish for the service environment — plated steel for general use, stainless for corrosion resistance.
- **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- **Standard:** This product is supplied to DIN 3126 / ISO 1173 (C6.3 hexagon drive). Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

## Where Magnetic Bit Holders and Extensions Are Not the Right Choice

Match the fastener to the load, environment and whether the joint must be reopened; the wrong class or style is the usual cause of joint failure.

Custom manufacturing · Made to drawing

## Need a magnetic bit holders and extensions outside the standard range?

A non-standard fastener tool is quoted from the drawing; where one already exists in the catalog, the special is usually a variation on its tooling.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom fastener tool manufacturing](https://engineeringhardware.com/custom/tools/)[Send a drawing](https://engineeringhardware.com/custom/tools/#rfq)

## Technical Drawing

Dimensioned line drawing of magnetic bit holder Magnetic Bit Holders and Extensions to DIN 3126 / ISO 1173 (C6.3 hexagon drive). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Drive:** 1/4 in hex shank, C6.3 socket
- **Typical length:** 60 mm
- **Retention:** magnet

## Dimensions & Specifications (DIN 3126 / ISO 1173 (C6.3 hexagon drive))

| Form | Drive | Typical length | Retention |
| --- | --- | --- | --- |
| magnetic bit holder | 1/4 in hex shank, C6.3 socket | 60 mm | magnet |
| magnetic bit holder | 1/4 in hex shank, C6.3 socket | 150 mm | magnet |
| quick-release bit holder | 1/4 in hex shank, C6.3 socket | 75 mm | ball detent, sprung sleeve |
| bit extension bar | 1/4 in hex shank, C6.3 socket | 300 mm | magnet |
| square-drive bit adaptor | 3/8 in square to C6.3 | 50 mm | ball detent |

Inside the plant

## Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift.
2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g.
3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1.
4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227.

## Frequently Asked Questions

### What are Magnetic Bit Holders and Extensions used for?

Installing, adjusting or servicing the assembly rather than forming part of it. They are supplied to DIN 3126 / ISO 1173 (C6.3 hexagon drive).

### Which industries use Magnetic Bit Holders and Extensions?

They are commonly specified in general machine building, maintenance & repair (mro) and fabrication & metalwork, among other sectors.

### How do I choose the right size of Magnetic Bit Holders and Extensions?

Match the size to the mating part using the dimension table on this page.

### Are Magnetic Bit Holders and Extensions made to a recognized standard?

Yes — they are manufactured to DIN 3126 / ISO 1173 (C6.3 hexagon drive), so dimensions are interchangeable between suppliers when you quote the standard on your order.

### Can I get a quote for Magnetic Bit Holders and Extensions in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.

## Related Pages

Product page: [Magnetic Bit Holders and Extensions — specifications & sizes](https://engineeringhardware.com/fastener/magnetic-bit-holders/)

### Magnetic Bit Holders and Extensions Specification Guides

### Related Fastener Applications