Before I knew anything about vaping, I started with a CCELL M4, a fixed 3.6V battery that came with a cart. I looked up the price to purchase separately online; it was less than $5.

I wanted more heat, so I upgraded. Perplexity recommended the Yocan Wulf Uni Pro, which goes up to 4.2V. But I was disappointed. It didn’t even heat as well as the CCELL. It also needed a tiny metal adapter on the cart so the cart could reach the magnetic contact. That adds a step and a small part I could easily lose, with no discernible advantage.

The directions also said not to charge it for more than two hours. What if I plug it in and forget? That made me wonder whether Yocan has any engineers who can design a proper charging circuit, or whether it’s a pure marketing company.

Brass Knuckles’s Barrel worked much better. At 4.0V it was noticeably hotter than the CCELL. Hooray! It’s a simple, single-piece design.

I received no incentive to write this review. I just felt moved to add some signal to the noise around vape batteries.

Verdict: Brass Knuckles Barrel, recommended. Yocan Wulf Uni Pro, skip.