My technical review of the MM Kobalt 'Multi Fit' Wrenches

Throughout the holiday deals and hype (aswell as working for Lowes), I kept seeing numerous ads and post blasting about the Kobalt Multi Fit wrenches.

As much as I wanted to buy them just because of the cheap price of $9.98, I held back, because I had this overwhelming concern that even for a DIY'er or a professional wrencher, it just seemed to gimmicky, it fit spline nicely, torx nicely, even 4 pointers, but I felt like it could and would strip hex nuts. That's when I noticed even the plastic hex nut you could try the wrench on in the store, was also starting to round.

I decided to buy them anyway, if not for weekend wrenching, for the back of the trunk.

The tools I used in this review was, a HF 6" digital caliper, a grade ??? 14mm galvanized hex bolt, a 13mm Snap-on 12pt combination wrench (for shown caliper accuracy), a 14mm 12pt Pittsburgh wrench, a 14mm Kobalt crossform wrench, and of course the 14mm Kobalt multi fit wrench (the likes of which was completely coated in oil to prevent the apparent easily rustable exposed non-chromed metal..


Please bare with me if I made any verbal mistake, or took any bad lighting shots, and I'll fix it.

The first thing I did was measure the galvanized 14mm hex bolt with the HF caliper to show it's accuracy, it came in at exactly 14.00 millimeters.

Here are my results.



The next thing I did was measure the open end side of the 14mm Kobalt multi-fit wrench for curiosity and came up with an promising 14.05MM.


I then measured the open ends of a Kobalt Crossform 14mm wrench, and a Snap-on 13MM combination wrench (different size done to show accuracy of caliper). I came up with 14.26MM, and 13.00MM respectively.



Afterwards I took a close up shot of the 14mm hex bolt in the closed end of the multi fit wrench, which to me you can EASILY see a MAJOR GAP between the actual wrench and the hex bolt. Combine with the fact that this is Taiwanese manufacturing, it seems obvious what would happen if you're pulling on this hard enough, or using some sort of cheater bar or pipe. Eventually the wrench closed end is going to spread from the gap, or bend enough where it will strip the bolt, causing more problems.


Afterwards I took a shot of it in a a Pittsburgh 12pt 14mm combination wrench, which surprisingly came in at an astonishing 14.02MM (although I can't speak for the quality or forging process of the steel).


Just to show the difference of 14.02MM versus roughly 14.30MM give or take, it's roughly a perfect fit compared to a major noticeable gap.


I know I kinda went crazy by posting a review of a $10.00 Taiwan wrench set on Christmas Eve, but I figured I'd do my part to the knowledge on this forum!

I hope by using different size wrenches, and multiple brands it would help help with an overall review of the wrench set itself in general , as well as compared to other brands.

Merry Christmas ! & Thanks for reading!

How did you measure the box end of the wrench?

Avgas said:

How did you measure the box end of the wrench?

Click to expand...

While probably inaccurate, I -attempted- to with the caliper on the multi fit wrench just to see what it'd come up with from one end to the other. It was roughly roughly 14.30-14.50 depending. While inaccurate (the reason I didn't try it on the other wrenches) I used a photo to show the major gap.

I measured the open ends for curiosity and to show the differences in the manufactures in general as an idea of the overall quality of the wrenches.

It's cool to see the open end clearances, I'm gonna measure my snap on set at work. The box end could be measured accurately with feeler gauges.

I was quite surprised at seeing a flawed finish, crooked stamped Pittsburgh open end come in at a 14.02 compared to a cross forms 14.26 (the likes of which are $79.99 when not on sale). However I can't speak for the quality of the steel/metal under extreme pressure.

Great review.

I would note that like the modern wrench "drive" types, the multi-fit is not designed to have a flat surface parallel with the bolt face, but rather uses the spline drives to make contact near the corners (points) of the hex head.

As such, it's difficult to quantify the fit of the multi-fit. It looks like it would make decent contact with the 14mm bolt, but clearly it should not be used and is probably not marketed to loosen rusty fasteners.

I'd say that due to this, there are more important factors than whether or not the wrench is exactly 14.0001mm as the force is placed on the edges of the fastener, and the wrenches rigidity and steel quality is likely more important than this distance?

On the multi-fit, I would compare versus box end wrenches by measuring the distance between the two points of the hex head, and then between two opposing splines on the multifit or box end. This would give you an idea of how much contact area there are between the two, which is important.

Ishiboo, I think you brought up some excellent points in your post, and they're appreciated.

I do agree 100% that the quality of the steel does make a significant impact on whether or not the gap could cause a problem or not.

I might pick up a SAE set for the price, just because I scarcely work on SAE, and it'd be interesting to have some multi-fits for SAE fasteners.