Short answer: pick the plate that matches your PACKOUT box. Half width for compact boxes, organizers, crates and the 16 qt cooler. Full width for standard tool boxes, drawers, organizers and crates. Center only when you want to lock a full-width box by its center feet in a tight spot. Triple XL holds one full-width plus one half-width box, or three half-width boxes side by side. Half-width boxes fit on every plate we make.
What is a PACKOUT undermount plate?
It's a flat steel or aluminum plate with the PACKOUT locking pattern laser-cut into it. The mounting hardware goes in from underneath, so the top stays flush and nothing sticks up between the plate and your box. Your box sits lower, locks in the same way it does on a stack, and the install looks factory.
Every BOCO undermount plate is made in the USA in Apple Valley, California.
Undermount plate sizes and load ratings
| Plate |
Size (approx.) |
Holds |
Wall load |
Floor load |
Price from |
| Half width |
14.5" × 8.5" × .75" |
One half-width box |
37.5 lb |
75 lb |
$85 |
| Center only (for full width) |
14.5" × 10.5" × .75" |
One full-width box, by its center feet |
50 lb |
50 lb |
$95 |
| Full width |
14.5" × 18.5" × .75" |
One full-width box or one half-width box |
75 lb |
150 lb |
$110 |
| Triple XL |
30" × 13.5" × .75" |
One full + one half, or three half-width boxes |
150 lb |
300 lb |
$140 |
Load ratings assume appropriate hardware installed into a suitable structure. Aluminum plates carry the same ratings as 14-gauge steel. Prices are for raw steel; powder coat and aluminum cost more.
Materials and finishes
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14-gauge steel (about 0.075"): the standard. Strong, weldable, paintable.
-
1/8" aluminum (0.125"): lighter and won't rust. Good for bikes and anything that lives outside.
-
Finishes: uncoated (ready to paint or weld), textured black powder coat, or red powder coat.
Holes your way
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Standard: pre-cut mounting slots or holes, ready to bolt down.
-
No holes: a clean plate so you can drill your own to fit any rack.
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Relocated: send us your rack or bolt pattern and we'll cut the holes where you need them. Contact us for a custom pattern.
Compatible Milwaukee PACKOUT part numbers
These Milwaukee PACKOUT boxes, organizers, crates and coolers lock onto BOCO undermount plates. Rolling boxes are not listed because they don't mount to plates.
| Milwaukee part # |
Milwaukee PACKOUT product |
| 48-22-8422 |
PACKOUT Compact Tool Box |
| 48-22-8424 |
PACKOUT Tool Box |
| 48-22-8425 |
PACKOUT Large Tool Box |
| 48-22-8429 |
PACKOUT XL Tool Box |
| 48-22-8450 |
PACKOUT Tool Case with Customizable Insert |
| 48-22-8442 |
PACKOUT 2-Drawer Tool Box |
| 48-22-8443 |
PACKOUT 3-Drawer Tool Box |
| 48-22-8447 |
PACKOUT Multi-Depth 3-Drawer Tool Box |
| 48-22-8445 |
PACKOUT Cabinet |
| 48-22-8430 |
PACKOUT Organizer |
| 48-22-8431 |
PACKOUT Low-Profile Organizer |
| 48-22-8432 |
PACKOUT Deep Organizer |
| 48-22-8435 |
PACKOUT Compact Organizer |
| 48-22-8436 |
PACKOUT Low-Profile Compact Organizer |
| 48-22-8440 |
PACKOUT Crate |
| 48-22-8437 |
PACKOUT Compact Crate |
| 48-22-8438 |
PACKOUT Low-Profile Crate |
| 48-22-8439 |
PACKOUT XL Crate |
| 48-22-8043 |
PACKOUT Wire Pulling XL Crate |
| 48-22-8460 |
PACKOUT 16qt Compact Cooler |
| 48-22-8462 |
PACKOUT 40qt XL Cooler |
Real builds
Center only on a Suzuki DR650
Matthew bolted our center-only undermount to the rear rack of his Suzuki DR650. He rides with the bare plate, a crate, drawers or an organizer, whatever the trip calls for. His review: "It's amazing. I love it."
Half width on a Honda XL750 Transalp
A half-width undermount bolted to the rear rack of a Honda XL750 Transalp. Bare mount when riding light, and the PACKOUT 16 qt cooler clicks on for the long haul.
Where it mounts
Motorcycle tail racks, scooters, ATVs, side-by-sides and UTVs, center consoles, truck beds, trailers, van floors and shop walls. Anywhere mounting space is tight and you want the box to sit low.
Frequently asked questions
Which plate do I need?
Match the plate to your box. Half width for compact boxes, full width for standard boxes, center only to lock a full-width box by its center feet, and Triple XL for one full plus one half, or three half-width boxes side by side. Half-width boxes fit on every BOCO plate.
Do Milwaukee PACKOUT rolling boxes work with an undermount plate?
No. Rolling boxes are designed to be the bottom of a stack and don't lock onto a mounting plate.
How much weight can it hold?
Half width: 37.5 lb wall, 75 lb floor. Full width: 75 lb wall, 150 lb floor. Center only: 50 lb wall, 50 lb floor. Triple XL: 150 lb wall, 300 lb floor.
Steel or aluminum?
Steel is the standard and can be welded. Aluminum is lighter and won't rust, with the same load ratings.
Can I get it without holes, or with holes moved?
Yes. We can leave the holes off so you can drill your own, or cut them to match your rack or bolt pattern.
Is mounting hardware included?
No. Every rack and surface is different, so the right hardware is up to the installer.
How fast does it ship?
In-stock plates ship in 1–2 business days. Made-to-order plates ship in 1–2 weeks.
Shop the PACKOUT undermount plate →
Made in the USA by BOCO Custom LLC, Apple Valley, California. Milwaukee® and PACKOUT™ are trademarks of Milwaukee Tool. BOCO Custom LLC is not affiliated with or endorsed by Milwaukee; brand names and part numbers are used only to describe compatibility.
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