^ that looks like a rebadged push button shift /brake lever combo. It even has "1,2,3" gears in the little window.
It's kind of like a ratcheting come-along deal; each push of the button pull the cable 3/8-1/2 an inch then grip it. The other lever releases the ratchet pawl.
One hesitation is if you need to declutch in a panic like if a chain goes berzerk it might take two button presses to get it done.
My set up is an old brake lever in the "primary" left position running clutch, and my right brake lever now runs the front brake. (same as a motorcycle so far). If one looked at the left side of my handlebar tube the clutch would be at 8 oclock. Put the rear brake lever on the left side at 12 oclock. If I need it, which I normally ride with the safety margin that I wouldn't, I would grab straight down with my hand and pull on the handlebar itself with my four fingers and grasp the lever in the Vee of my thumb. Hope that makes sense.
