I see.
Well, I think there are only 2 main choices in 30mm fet drivers that use momentary switches. There is the Texas Avenger one that is not commonly available. You have to make it yourself or have someone make a batch of them like Lexel is doing right now. With this one you can get the Narsil ramping firmware.
The other is THIS one Richard at MTN Electronics makes. I don’t think he has Narsil available so it’s just multiple levels like a normal light.
There may have been some older drivers, but I’m too new around here to know for sure.
I found some details on DBCustoms driver. He took a 17mm DD and zener modded it then added TK’s ramping firmware. Check out his video here.
For a detailed description, go to youtube and look below the video.