AB= Applied Ballistics. I agree with the one and done. I plan on using my Leica HD-Bs for the spot and stalk hunting. (When they ever ship) And the Vectronix when we are set up stationary. I had sold my PLRF15 and I really wasn't looking to get another Vectronix, but with the new features, I couldn't resist. LOL...... I did find myself one day in a snow storm in Colorado trying to range four bulls in a herd we had crept up on. We could not get a good reading with the original HD-B's. My Terrapin was sitting in the truck four miles away, nice and dry. I didn't take it because the snow had stopped and the sun came back out. Without phone service, we were unable to see the radar. Within an hr, it was pounding snow again. We never took a shot. My son wasn't happy......
I had tested the Original G7, HD's and Terrapin side by side in rain and snow and the Terrapin always ranged much further than the others.