Engine Leak Down Tester Quickly tell - from the outside - when your engine needs an overhaul! This easy-to-use tester checks ring seals, valves, even head gaskets. Do not wait too long to rebuild that expensive motor - but do not do it too soon either! Allows the ability to achieve consistent power. Stretch out the time between costly teardowns. Rugged design features rubber bumpers to protect the gauges. Exclusive Longacre gauge manifold meters the airflow for precise readings. 0-3000 lbs. by 1 lb. Travel to .001". 6" to 20" tall springs. Coil and coil-over springs, square end and pigtail. Includes easy-to-use digital indicator to measure spring travel and a digital load readout. IMPORTANT NOTE- You MUST preload the spring to a minimum of 1/2". Manufacturers rate springs with a higher preload. The higher the preload, the higher the spring rate because the end coils start to touch, effectively shortening the spring. Without adequate preload, readings may be inconsistant. Coil springs - even the best quality - can vary as much as 5% from the stated rate. This is normal manufacturing tolerance.