The ESCO's (or mine, anyway) have a rubber insert. The E46's jack points also have a rubber insert. Rubber on rubber... no paint or undercoat scratching, no rust, and good grip. Under (above) the pads is a channel, in the shape of a symmetric cross. The channels accept a special shackle for lashing the cars down on a ship. (They don't work on tow trucks, because they need the springs blocks to keep the lashings tights.)
But, be careful. A lot of people have had their E46's rear jack point collapse if the entire side of the car is lifted off the ground from the rear jack point. I avoided this by cutting a bunch of 2" x 6" boards, 2 and 2.5 feet long. I'd jack the front and built a pad under the tires (two boards wide), and let the car back down onto the boards. Then, I'd do the back. Then, I'd repeat two or three more times, adding boards, until I could get the jack stands under the car.