By contrast, ski engineers do all kinds of math problems based on weight distribution to figure out where the bindings should be placed on a women-specific ski. Ski manufacturers have generally found that women's bindings should be about two centimeters farther up than men's, and women's skis reflect this with a forward binding mark. Proportionally speaking, men tend to have more weight around their shoulders; therefore they shift weight with the upper body. Women's concentration of mass tends to be lower, around the hips. They rely more on the lower body to initiate weight transfer. On skis women's weight is concentrated more toward the tail. In ski instructor lingo, this puts women "in the backseat." Moving the binding up a little compensates for that.