August 2016

Wismec/Jaybo Theorem: Amazing flavor but with some issues


By John Castle

The rebuildable dripping atomizer is known for its flavor but, generally, not for its eliquid capacity. Rebuildable tank atomizers, conversely, are known for good flavor and e-liquid capacity, but haven’t exactly been the easiest devices around which to build. There is certainly a market for a device with the flavor fidelity, vapor production, and ease of building of a rebuildable dripping atomizer, but with the more generous e-liquid capacity of a rebuildable tank atomizer.

Would the Theorem — inspired by SuckMyMod, designed by JayBo, and produced by Wismec — be that device? I took the $20.95 “plunge” to find out.

The Theorem arrived from MyVaporStore comes in a clear-fronted plastic case which was, mercifully, easy to get into and, on its back side, surprisingly informative. A diagram of the device and a listing of its component parts appears in easily readable white on a black background. Above the diagram, a list of included parts appears; however, the list below is slightly modified, as some parts arrive both installed in the device but also have separate “spares” in the box:

  • 1x Theorem Atomizer (Assembled)
  • 2x Airflow Control Rings (single and dual)
  • 1x Stainless Lined Glass Sleeve
  • 2x Glass Sleeves (one pre-installed; one separate)
  • 2x Notch Coils (one pre-wicked, pre-installed; one pre-wicked and separate)
  • 3x O-Rings (Cyan)
  • 4x Screws
  • 1x Hex Key
  • 1x User Manual

Unlisted in the components list is a narrow-bore glass drip tip. The entire set of contents rests on and under a soft black foam insert for the mod and spare tank, making extraction quick and painless, while the manual is concise and well-written, making preparation to use the device almost a snap. I’ll touch on that “almost” again shortly.

Specs & Features

The Theorem is a 22mm, 510-threaded, top-fill device, making it compatible with nearly every regulated mod on the market. As noted in the components list above, it features airflow control suitable to both single-coil and dual-coil builds. Its materials are stainless steel and glass (though whether the glass is Pyrex or quartz glass is not disclosed; I will assume Pyrex is the type in use here.) That tank sports an eliquid capacity of approximately 2ml.

The Notch Coil, both the one pre-installed and the spare in the box, are rated at 0.25 ohms of resistance and are composed of 316 stainless steel; this makes the Notch Coil compatible with a wide range of temperature control mods. I tested mine with the Hohm Slice by Hohmtech.

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Build Quality

The build quality of the Theorem is excellent in many respects, but quite lacking in one major way. First to the good: The machining is spotless, and there was no noticeable oil or other residues in or on the device out of the box. It was almost ready for use as soon as it was removed from the box and juiced up.

However, there were two areas in which the device was not quite ready for prime time; one was fixed with a little pre-filling modification: as pre-installed, the Notch Coil had quite a bit more wick installed than was necessary or desirable. This was easily solved by simply giving the ends of the wick a modest trim, wetting the wick, then using the included Hex Key to compress the wick more fully into the Theorem’s wick channels.

The second, and in my opinion the far more serious design issue, was the airflow control system. Notably, the airflow control rings are fully detachable. How did this impact my use of the Theorem? It made adjusting airflow a matter of guesswork; in the first place because, once the final (top-most) component of the top cap is installed, the airflow control ring aperture or apertures are no longer visible — and, in the second place, because the only anchor for the airflow control ring becomes your own grip on the airflow control ring as you screw down that final piece with your other hand. This is a problematic design choice, and one I look forward to seeing corrected in a Version 2 iteration of the Theorem.


With the wicks properly trimmed, and with the airflow set properly for my intended liquid’s strength and my preferred wattage output, I found that the Theorem does indeed deliver fully on the performance characteristics I have come to expect from a rebuildable dripping atomizer. At 65 watts on the Hohm Slice, the Notch Coil performs very, very well. Flavor fidelity is outstanding, throat hit is fulsome, and vapor production is also first-class.

However, when putting the mod into Temperature Control mode and setting it for 316 Stainless Steel, the mod returned a “Damaged Atomizer” error. Comparing that to the same mod’s performance with the 316 Stainless Steel atomizer head for my Uwell Crown, where that error did not occur, I have to assume that the error was caused by the Notch Coil rather than by the mod. This was something of a disappointment.

Availability & Price

The Theorem is available through many online retailers; my favorite is MyVaporStore due to their low prices and fast shipping. The Theorem can be had from them for the price of $20.95 plus shipping.

Recommendation & Conclusion

Would I recommend the Theorem? Let me break down the Pros and Cons:


  • Easy To Use
  • Flavor Fidelity
  • Vapor Production
  • Low Cost


  • Problematic Airflow System
  • Wick Trimming Required For Notch Coils
  • Low e-liquid Capacity

Overall, for its low asking price, RDA-like performance and slightly-greater-than-RDA level e-liquid capacity, I can’t dis-recommend it. In the areas where it delivered, it was spot on. With that said, I found the hiccups to be frustrating. My recommendation is to wait for a Version 2.