Strawberry jelly.
But I could be mistaken. I have never had the guts to dig past all the potting to find out what makes a Malkoff, a Malkoff. But whatever is there is going to make the module run for a very long time, as they are very efficient.
You have two options - open one up yourself and let me know about the jelly. Or call/email Gene and he may be very happy to explain why his modules are so good.
However, there is a chance that his circuitry is highly-guarded proprietary information. I suspect that it is just good solid engineering with careful attention paid to the assembly, with top-notch componentry. No secrets, no magic.
It's the same as any other P60/D26 drop-in. Except better. And no low voltage cutout. And it has strawberry jelly. Who doesn't love strawberry jelly???