This means that both tip and tail are raised from the snow, and that the board can be ridden switch. A pure twin is a board that is shaped identically on each side of it's center point, and has the same flex pattern in it's nose and tail. This is a game of nuance and will make less difference to the ride than other features. Softer noses will also help in powder, but are a little unstable when riding switch. Many first time buyers become focused on the differences between manufacturer's approaches towards tip and tail construction.
Some brands argue that wood in the ends is the way to go for a consistent flex pattern.
Others state that you need fiberglass for low swing weight. Some argue that extra metal edge should be laid in, to protect from damage, while others feel this added weight is unacceptable. Truth is, it really doesn't matter much at all. No type of end structure will prevent against this. Metal edges all around, when struck hard, often wedge themselves into the board, creating more damage than had they not been there.