IWISS SN-025: Another head scratching “DuPont” crimp tool lands

Following on from my recent review of the Preciva PR-3254 crimp tool, I hit up eBay and Amazon to see if any other such tools may have surfaced lately. I found one:


We have a new tool (Amazon UK link), which is also apparently specifically designed for these terminals. At the time I wrote this article, the SN-025 is not (yet) listed on IWISS’s website?

Two terminals apparently crimped with the IWISS SN-025. A “DuPont” terminal, and, err, what’s that other one? One auction listing mentions TE “Superseal” terminals, which look quite different to the one on the white wire. Recognise it? please drop a comment.

The above graphic is provided by the Amazon seller, specifically pointing out that it wraps the insulation around the wire. It’s almost as-if they’ve been reading my crimp connectors page

While this is being sold as a “DuPont” crimp tool, it appears it is predominantly designed for another type. It has three dies:

  • AWG 28 for “DuPont” terminals?
  • AWG 20 for mystery larger terminal
  • AWG 18 for mystery larger terminal

The AWG 28 die

DuPont HT-95. The gold standard which I’ll be comparing against.

Let’s put some “DuPont” terminals in there and see what we end up with:

Of course SN-025 wasn’t going anywhere near the HT-95’s crown as ultimate “DuPont” crimp tool but it did do marginally better than the Preciva PR-3254 I reviewed previously.

The SN-025 not having an AWG 24 die, it over-crimped the insulation as we would expect, and the wire part isn’t crimped anywhere near as tight as it is supposed to be – typical for Chinese tools.

Verdict: Pass (for non critical applications).

If we were to cut open the wire parts of the DuPont vs IWISS crimps, we would find something like this. For the SN-025, likely a lot worse. Source: TE Connectivity

The other two dies?

I went through my crimp tool cupboard to see if I had any others like this. Of the, err, considerable number (I’ve lost count) of manufacturer original tools in my collection, just seven have an ‘O’ type insulation crimp. Only two of those were in this wire size range:

Top: TE Multimate crimp tool. Bottom: TE Economical Interconnect crimp tool

TE Multimate

An interesting type to compare against because Multimate terminals look quite similar to the one pictured in the image the tool is sold with. This tool may be designed for use with a similar type of connector of Chinese design/origin. Given how esoteric these are, no point in going any further into that.

Economical Interconnect

A common type stretching to AWG 20 wire size, which has an ‘O’ crimp. More about these here.

KK .396 (?)

Lost in translation? The range of terminals apparently crimped by this tool. Always good to have something to handle those Micro Timers.

In addition to the “DuPont” types, Molex KK .396 (.156″) is offered as a supported terminal type. Not something the average hobbyist is going to be reaching for. I’ve got the manufacturer original tool for these, it’s not quite an ‘O’ type crimp, but let’s give it a shot anyway:

Mini-Fit Jr (?)

The die in the manufacturer original tool is quite similar to the KK .396 tool, so we’ll look at these too.

Certainly not one for E.I. It was OK on the wire part but it didn’t touch the insulation crimp. Verdict: Fail.

For KK .396. Pretty good! the insulation part is a tad too loose on AWG18 wire (forget it for AWG 20). The results do not match the marketing image, I can only assume that was done by a different tool. Or, perhaps, the marketing image is depicting a smaller KK .254 terminal? Verdict: Pass.

Last but not least, it did a really good job on Molex Mini-Fit Jr. I’m so impressed with the results that I’ve decided to take a closer look:

AWG 18 wire crimped by 3 tools. On the left a typical result of a budget tool, with the insulation deeply pierced due to the very long tabs on these terminals.

For the SN-025 crimp on the right: It takes a bit of practice, and I’ve accidentally nicked the wire because I positioned the terminal too far forward, also the AWG 20 die must be used. The SN-025 has yielded a result very similar result to the Molex 63819-0900, correctly and cleanly wrapping the insulation support. The best I have ever seen from a budget tool.

Verdict: Pass.


Without a specification from the manufacturer, and subsequently knowing what it was actually designed for it’s difficult to give it a final judgement. Wire crimping force is quite respectable for larger terminals i.e. KK.396 / Mini-Fit Jr, but not so great for “DuPont” terminals.

As always my recommendation is that this tool (and any other tool in this price bracket) should only be used for applications in the “fun” category, specifically the kind of fun that doesn’t involve someone losing an eye when it goes wrong.

Manufacturers of tools around this price do not spend any time ensuring that the tools they produce crimp terminals to the specifications of a specific type, instead they are a broad brush design intended to crimp a range of terminals to a vaguely presentable standard. Yes we’ve got some nice crimps on Mini-Fit Jr, but that is purely luck, and only achievable with very specific terminal placement during crimping.

If you’re building something critical and/or expensive, name brand terminals and the manufacturer tool should be used. I have detailed a lot of these on this page.

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