They’re for bending LARGE pieces of PE. lol I gotta confess, I don’t know what the counter ball is. A press can be a dangerous piece of equipment. Saw plenty of injuries over the years. Thankfully, I don’t have to work quite as hard these days.
Hi;
The Counter Ball is the big Orb or Capsule shaped piece of iron on the handles that helps the bottom( The Folding Brake) to return to upright after the bend. It has just enough weight to bend without messing up the line. Kinda like a Counterbalance.
I had to laugh when I went to a sign shop. They folded the edges. Well, they had this harness and spring loaded arm retractors so’s ya wouldn’t get your hands caught in it .Can you believe that?
I have to comment again-Sorry:
I have bought the “Cat’s Meow” P.E.Tools. I have used either one of them off and on. I have the Big one, I have the Bug , and others. What do I use ? Two utility knife blades slightly dulled, edge to edge ,I slide one under the P.E… For really long stuff I use two stainless rulers that I ground the edges perfectly square and then mounted one on a board, used blind nuts in three spots and Wing nuts to secure it, then I fold the other one up. Three Doll House hinges . That’s for the long pieces. Kinda like a table top Bending brake that won’t hurt you!
Tanker-Builder, I got it. You’re speaking of a leaf brake. Where you clamp a piece of material between 2 plates, dies, whatever and then the bottom leaf rotates up to bend the material. I’ve used an old very large one that was all hydraulic and didn’t have any exposed counter balance.
Mainly what I have worked with are vertical hydraulic brakes. Generally a V shaped bottom die and a knife shaped top die. The ram cycles down to bend and then up to home position. Mostly with 14ga up to 3/16 material.
The leaf brake principle is more like bending PE. Clamping on a line and using a blade, finger, pliers to bend up or down.
Sorry for getting sidetracked folks 
Ha Ha!
I knew there was a name for that thing. Just couldn’t remember it!
I do an alot and that had to hurt alot.[:'(]
I got a medium one from the small shop for 1/700 parts. Before that o tried a flat piece of metal to put them on and another piece to try and hold it and another to make a bend. Yuck. This little tool has been much better for me. It also comes with a long sharp blade to use and free shipping I think. I also 1st tried tamiya bending pliers. No good as they didn’t close all the way