Model’s 135, 172 & 29 = 20 (low stiffness rating)
Model’s 120, 220, Lolly = 25 (med/low stiffness rating)
Model Jack = 30-35 (med/high stiffness rating)
Model 336 = 40 (med/high stiffness rating)
Model Jack 2 = 45-50 (high stiffness rating)
Model 3200 = 70 (very high stiffness rating)
