The method
How to pick a stacking system you will not regret
This is not a box purchase, it is a commitment. The switching cost is the whole stack, so the question to answer first is not which system - it is whether you need one.

Answer three questions in order. Do the tools actually leave the garage? If not, buy a steel cabinet instead. Do you already own boxes from one family? If so, that decides it. What is the heaviest thing you will carry? Under 100 lb opens the field; over it, the 250 lb systems are the only real options.
1. Do you actually need a modular system?
This is the question the category never asks, because everyone selling into it has an obvious answer. Per dollar, a steel rolling cabinet stores several times as much as a modular stack and holds several times the weight - a single 56-inch cabinet drawer can be rated at 120 lb per pair, eighteen times over, against 250 lb for an entire rolling stack.
What modular buys is portability and weather sealing. Both are worth a great deal if the tools go to a job site, a track day, a friend's driveway or a second property. Both are worth close to nothing against a garage wall. The comparison, properly.
2. What do you already own?
If you have a shelf of first-generation ToughSystem boxes, ToughSystem 2.0 is backward compatible with them and the decision is effectively made. Nothing PACKOUT offers outweighs not throwing away boxes you already have.
If you own nothing, this question does not apply and range size becomes the tiebreaker - which is where PACKOUT's considerably larger accessory range earns its reputation.
3. Weigh the heaviest thing you will carry
Published capacities in this category span a factor of five, from 50 lb per box to 250 lb for a rolling base. That is not a marketing spread, it is a genuine engineering difference, and it maps directly onto trades.
| What you carry | Rough weight | What it implies |
|---|---|---|
| 200-piece mechanic's socket set | about 24 lb | One item is half a 50 lb box |
| 1/2 in impact socket set | about 18 lb | Two of these and a 50 lb box is done |
| 22-piece combination wrench set | about 11 lb | Manageable in any system |
| Cordless drill plus two batteries | about 8 lb | Manageable in any system |
| Hammers and pry bars | about 14 lb | Heavy for a 50 lb module |
Weights are published product weights rounded to the pound. Automotive tooling reaches a 50 lb module limit far faster than electrical or carpentry tooling does.
4. Then, and only then, compare the systems
- Capacity: PACKOUT, ToughSystem 2.0, Klein MODbox and StackTech publish 250 lb rolling bases. Ridgid publishes a 100 lb cart.
- Weather: PACKOUT and ToughSystem 2.0 publish IP65. The others do not publish a rating.
- Range: PACKOUT is the largest by a clear margin.
- Compatibility: ToughSystem 2.0 is backward compatible with older ToughSystem; nothing else here is compatible with anything.
- Width: Ridgid's 22 in boxes take long tools that others cannot.
The switching cost nobody puts in the comparison
Cleat and latch geometry is proprietary to each family. There is no adapter worth using, and mixing systems means owning two stacks that do not attach to each other - which is strictly worse than owning one of either.
So the real cost of choosing wrong is not the first box, it is the fourth. Buy the base of the system you can see yourself in for five years, buy one module, and use it for a month before buying anything else. The ranges are large and it is remarkably easy to buy modules for a workflow you do not have.
Common questions
Are modular tool boxes worth it?
Only if the tools leave the garage. Per dollar a steel rolling cabinet stores several times as much and holds several times the weight. Modular systems buy portability and weather sealing, which are worth a lot on a job site and very little against a wall.
Which modular system should I buy if I own nothing?
If you carry heavy tools, one of the 250 lb systems - PACKOUT or ToughSystem 2.0. Between those, PACKOUT's larger accessory range is the tiebreaker for a buyer starting fresh. The comparison.
Can you use an adapter to mix modular tool box systems?
Not in any way worth doing. Cleat and latch geometry is proprietary to each family, and mixing means owning two stacks that do not attach - strictly worse than owning one of either.
Sources
Read next
Best modular tool storage systems, on the numbers they publish
Five systems compared on published dynamic capacity, weather rating and range size, with the 50 lb versus 250 lb gap that decides it.
Tool chest vs PACKOUT: two answers to two different questions
Storage per dollar against portability, with the numbers laid out and one question that decides which you should buy.
PACKOUT vs ToughSystem 2.0: identical headline specs, one real difference
Identical headline specs, one real difference: backward compatibility against range size, and the dynamic-versus-static trap in between.
Milwaukee PACKOUT, explained by its own specification sheet
How PACKOUT works, what its two published capacities mean, what IP65 covers, and which piece to buy first.
DeWalt ToughSystem 2.0, and the one thing PACKOUT cannot do
The published numbers, the tower, and the backward compatibility that is the one axis where it beats PACKOUT outright.