You sell on Shopify and Amazon. Your 3PL uses ShipHero. When an Amazon FBM (Fulfilled by Merchant) order comes in, you might notice your products are set up as “kits.”

These aren’t real kits. It’s a clever workaround you (or your 3PL) had to manually configure to solve a real problem.

The Problem

Your Amazon SKU: BLUE-WIDGET-AMZ
Your 3PL’s SKU: BLUE-WIDGET-001

When an FBM order comes from Amazon (meaning your 3PL ships it, not Amazon), ShipHero sees BLUE-WIDGET-AMZ and has no idea what to ship. The SKUs don’t match. ShipHero can’t just map one SKU to another. So your 3PL uses a workaround.

The Kit Workaround

Watch a 3PL demo how merchants set this up. Here’s the process:

Create a “kit” in ShipHero named BLUE-WIDGET-AMZ (your Amazon SKU)
Add BLUE-WIDGET-001 (the warehouse SKU) to the kit with quantity 1
When Amazon sends an FBM order for BLUE-WIDGET-AMZ, ShipHero recognizes it as a kit, breaks it down to the component (BLUE-WIDGET-001), and ships the actual product

Setup requirements:

The kit SKU must have exactly 0 on-hand inventory (as shown in the video demo. If it has any inventory, you need your 3PL to adjust it first)
The kit SKU can’t have bin locations (ShipHero’s documentation: “Please delete all bins this product is in before making it into a kit”)

Most merchants create brand new SKUs for kits to avoid both issues.

Clever. Works great. Until it doesn’t.

Where It Breaks

Beyond the setup challenges, the main ongoing issues are:

The CSV failures: With hundreds of SKUs, bulk uploads fail silently. A trailing space, a special character, a timeout, and some kits don’t get created. You only find out when orders don’t ship.

New product delays: Every new Amazon product needs a kit created manually. If your 3PL is slow or misses one, those orders get stuck.

Component stock-outs: If BLUE-WIDGET-001 goes out of stock, the kit shows unavailable. But if someone accidentally ships the last unit directly (not through the kit), inventory sync gets messy.

No audit trail: When something breaks, there’s no easy way to see which kits exist, when they were created, or if the mappings are correct. You’re debugging blind.

The CSV Upload Dance

For 10 SKUs, you set up kits manually. For 500, you maintain a spreadsheet and bulk upload using ShipHero’s template:

SKU,Component SKU,Quantity,Build Kit,Warehouse
BLUE-WIDGET-AMZ,BLUE-WIDGET-001,1,0,Primary
RED-WIDGET-AMZ,RED-WIDGET-001,1,0,Primary
GREEN-WIDGET-AMZ,GREEN-WIDGET-001,1,0,Primary

(Watch ShipHero’s official tutorial on bulk kit creation)

You upload it. Half the time it works. The other half:

Someone added a space after a SKU (upload fails)
A special character broke the encoding (upload fails)
The file was too big (100 line limit per upload, partial upload, no one notices)
ShipHero rejected rows without saying which ones or why

You find out when orders don’t ship.

Real Scenarios That Break This

Scenario 1: The Holiday Rush
Black Friday. You’re running FBM for faster delivery times. You uploaded 200 new kit mappings last week. But 20 of them had trailing spaces in the CSV. Those 20 products? Orders stuck all weekend. ShipHero support is closed until Monday.

Scenario 2: The Missing Kit
You add 20 new Amazon products. You create 19 kits but miss one. That one product’s FBM orders fail because ShipHero can’t find GADGET-AMZ in the warehouse. You don’t notice until customers complain about canceled orders.

Scenario 3: The New Product Launch
You launch 50 new products on Amazon. Each needs a kit set up in ShipHero. You create them one by one in the UI. Takes 3 hours. You miss 5 SKUs. Those products show “out of stock” on Amazon for days.

How to Check Your Current Setup

You can see your kit mappings directly in ShipHero:

Log into your ShipHero account (client side, not your 3PL’s view)
Navigate to Products > Kits to see all your kit configurations
Check which Amazon SKUs are mapped to which warehouse SKUs
Export the list if you need documentation

What You Can Do Today

If you’re setting up new kits:

Create brand new SKUs for kits (avoids the zero inventory issue)
Keep your own documentation of mappings
Test with one product before bulk uploading

If you already have kits:

Export your kit list from ShipHero for documentation
Check if any kit SKUs show inventory (they shouldn’t)
Set up a process for adding new products quickly

The Real Challenge

This kit workaround is actually pretty smart. It solves the problem using ShipHero’s existing features. The challenge is that it requires manual setup and maintenance for every SKU.

You need to:

Create each kit manually or via CSV
Monitor for inventory issues
Fix problems when they arise
Update mappings as you add products

It works, but it’s time-consuming, especially at scale.

How SKU Wrangler Helps

Instead of manually managing kit CSVs and hoping nothing breaks, SKU Wrangler automates the painful parts:

Automated Kit Creation: Connect your Amazon and ShipHero accounts. SKU Wrangler generates the properly formatted CSV or creates kits via API. No manual entry, no formatting errors.

Missing Kit Audit: SKU Wrangler scans your Amazon SKUs and ShipHero kits to identify gaps. Know instantly which products need kit mappings before orders fail.

Centralized Mapping: Track all your SKU relationships in one place. Amazon to warehouse, Shopify to 3PL, wholesale to retail, all documented and searchable.

Bulk Operations: Adding 100 new Amazon products? SKU Wrangler creates all the kit mappings in one operation, properly formatted for ShipHero’s requirements.

The kit workaround still happens in ShipHero (that’s how their system works), but you eliminate the manual CSV creation, the missing mappings, and the debugging headaches.

Bottom Line

If your 3PL uses ShipHero and you sell on Amazon, you’re probably using this kit hack. It works until it doesn’t. And when it doesn’t, orders stop shipping.

Now you know what to look for, what questions to ask, and what breaks. That’s half the battle.

New to FBM? Amazon’s FBM overview explains the basics. For FBM vs FBA comparison, see Amazon’s guide.

Ready to automate your kit management? Get access to SKU Wrangler.