Progressive-rate 3 rocker arms determine how much the compressive force at the wheel will vary with suspension travel. The higher the rate, the more the suspension will stiffen as the wheel moves upward. Rocker arms are available in 3 progressive rates with 1 having softest rate and 3 being the stiffest. Progressive-3 rockers reduce body lean and brake dive and provide the most responsive handling. Progressive 3 rockers require new push rods (sold separately). Use push rods 5319 or 5319X.