Milwaukee Packout Undermount Mounting Plate with Hidden Fasteners – Steel or Aluminum

A flush-top undermount plate for Milwaukee® PACKOUT™ boxes in half, full, full center-only and triple XL widths, in 14-gauge steel or 1/8-inch aluminum. The hardware sits underneath the plate, so your boxes sit lower and look cleaner. It is made for motorcycle racks, off-road vehicle consoles, UTV racks and custom tool walls. Standard plates include pre-cut mounting slots or holes, and you can ask us to omit them to drill your own.

Load ratings assume appropriate hardware installed into a suitable structure. Aluminum plates carry the same ratings as 14-gauge steel.

Where it mounts: motorcycle tail racks, ATVs, SXS and UTVs, center consoles, and anywhere mounting space is limited.

Need a different hole pattern or size? We make custom mounts. Contact us with your requirements, including custom powder coat colors.

Why an undermount plate

• Hidden fasteners: integrated mounting points keep hardware out of sight for a factory-installed look.
• Flush top surface: boxes sit lower and cleaner.
• Ready to paint or weld: uncoated plates ship deburred for fabricators.
• Steel or aluminum: aluminum is lighter and resists rust.

Frequently Asked Questions

Which size do I choose?
Half width for single PACKOUT boxes, full width for dual-width boxes, full width (center only) to secure a dual-width box using only the center feet, and triple XL for three boxes side by side.

What weight can it hold?
Half width: 37.5 lb on a wall, 75 lb on a floor. Full width: 75 lb on a wall, 150 lb on a floor. Center only: 50 lb on a wall and 50 lb on a floor. Triple XL: 150 lb on a wall, 300 lb on a floor. Ratings assume appropriate hardware installed into a suitable structure.

Can I order it without holes?
Yes. Standard plates include pre-cut mounting slots or holes. Contact us to omit them and drill your own.

Is mounting hardware included?
No. Mounting surfaces vary, so choosing the correct hardware for the installation is up to the end user or installer.

Do you make custom mounts?
Yes. If you need a different hole pattern or size, contact us with your requirements.

How long until it ships?
In-stock items ship within 1–2 business days. Made-to-order items ship in 1–2 weeks.

Shipping, returns and warranty: see our shipping policy, returns policy and warranty.

Want to cut your own?

We sell the DXF cut file for the half-width hidden fastener mount: Hidden Fastener Mount DXF, or browse all DXF cut files.

Made in the USA — BOCO Custom LLC. Milwaukee® and PACKOUT™ are trademarks of their respective owners. BOCO Custom LLC is not affiliated with or endorsed by them; brand names are used only to describe compatibility.

10-Gauge Mild Steel (0.1345" | A Little Over 1/8 Inch)

• Best For: Our Heavy-Duty plates: vehicle floors, truck beds, shop workbenches, and heavy modular tool stacks.
• The Advantage: Our stiffest steel. The extra thickness resists flexing, twisting, and rattling under heavy loads and daily job-site use, and it carries the highest load ratings we publish.

12-Gauge Mild Steel (0.1046" | About Two Stacked Dimes)

• Best For: Locking mounts for Husky Build-Out, Bauer, and DEWALT DXL, plus service vans, enclosed trailers, and standard shop layouts.
• The Advantage: A strong middle ground between strength and weight. It handles constant road vibration without adding unnecessary bulk to a mobile rig.

14-Gauge Mild Steel (0.0747" | About the Thickness of a Nickel)

• Best For: Light-Duty Packout plates, battery organizers, accessory mounts, and lightweight shelf accessories.
• The Advantage: A rigid, low-profile mount for lighter gear that keeps your layout clean and your weight down.

1/8-Inch Aluminum (0.125" | Light and Rust Resistant)

• Best For: Open truck beds, roof racks, exterior trailer sides, and wet or salty environments.
• The Advantage: Naturally rust resistant and about one third the weight of steel. It saves weight on a mobile rig and stands up to rain, snow, and road salt.

11-Gauge 304 Stainless Steel (About 0.125" | About 1/8 Inch)

• Best For: Exposed truck bed brackets, marine use, premium shop builds, and wet or corrosive environments.
• The Advantage: Strong, rigid 304 stainless that resists rust without paint or powder coat, even in road salt and harsh outdoor conditions. Available on select plates, made to order.

Note: Sheet metal gauge numbers run inversely. The lower the gauge number, the thicker and more rigid the metal.

We fabricate our mounting solutions and accessories from mild steel, aluminum, and 304 stainless steel, built for harsh job-site environments. Choose the right finish for your build and review our care recommendations below.

Uncoated Steel (Paint Ready)

• Overview: Shipped bare and untreated, straight from fabrication. Ideal for custom painting, powder coating, or welding into custom racks.
• Appearance: May show light mill scale, surface scuffs, or minor flash rust on delivery, which is normal for uncoated steel.
• Care & Maintenance: Uncoated steel will rust when exposed to moisture, humidity, or air. We strongly recommend cleaning and lightly sanding the surface, then applying paint, clear coat, or powder coat before installation.

Powder Coated

• Overview: A durable, baked-on powder coat finish that protects the steel against wear, corrosion, and UV exposure. Powder coat is made to order.
• Appearance: A smooth, uniform finish, textured black on most plates and red on select Packout plates, ready to install out of the box.
• Care & Maintenance: Clean with warm water, mild dish soap, and a soft microfiber cloth. Avoid solvents such as acetone or paint thinner, and avoid abrasive scrubbers, which can wear the coating. Touch up deep gouges or scratches promptly to protect the metal underneath.

Uncoated Aluminum

• Overview: A lightweight, naturally rust-resistant option, about one third the weight of steel. Ideal for open truck beds, work vans, and marine or wet environments.
• Appearance: Bare metal with a clean industrial look. Aluminum forms a thin protective oxide layer on its own. Light surface grain or manufacturing tool marks may be present.
• Care & Maintenance: Wash with automotive soap and water. Aluminum may dull or develop a light oxidation over time, which is normal. To restore the shine, use a standard aluminum polish.

Uncoated 304 Stainless Steel

• Overview: Strong and highly rust resistant, for exposed truck beds, marine use, and wet or corrosive environments. Available on select plates, made to order.
• Appearance: A clean, bare metal finish that needs no paint or coating.
• Care & Maintenance: Low maintenance. Clean with soapy water or a stainless steel cleaner to remove grease, road grime, and fingerprints. Avoid steel wool and chlorine-based cleaners, which can mark or pit the surface.

What is Proposition 65?

Proposition 65 (officially the Safe Drinking Water and Toxic Enforcement Act of 1986) is a California law. It requires businesses to warn California consumers if a product can expose them to chemicals that the State of California lists as causing cancer, birth defects, or other reproductive harm.

These warnings are required even when a chemical is present in very small amounts that may not pose a significant health risk.

California Proposition 65 Warning

⚠️ WARNING: Cancer and Reproductive Harm. Products sold on this website can expose you to chemicals including lead, nickel, chromium (hexavalent compounds), titanium dioxide (airborne, unbound particles of respirable size), toluene, ethylbenzene, and formaldehyde, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.

What our products are made from

Depending on the product, our items may include steel, aluminum, powder coat or paint (including spray paint), threadlocker, lithium grease, and plastics such as acrylic and acetal (Delrin). Metals and coatings can contain or release trace amounts of the chemicals above, especially during cutting, welding, sanding, or coating.

Why is this warning on my order?

BOCO Custom LLC ships products nationwide, so we include this warning to comply with California law. A Proposition 65 warning does not mean a product is unsafe or defective. It means a product may contain a trace amount of a listed chemical. We provide this information so you can make an informed purchase.