The Magnum Tools Pump Jack operates on a spring loaded cam lock for smooth and reliable operation. Engineered for years of trouble free use with no clutch to wear out. This state of the art system is much more reliable, safe and easier to operate than the older styles of pump jacks. An all aluminum and steel construction provides consistent use in all climates and weather conditions. The Pump Jack arm is adjustable and telescopes from 12 to 24 inches in width to accommodate the widest of scaffolding planks and also includes steel chain to keep your plank solidly in place.