TEST SPRINGS FROM 6" TO 18" IN LENGTHRATES SPRINGS 0-3000 LBS. IN 1 LB. INCREMENTSMEASURES TRAVEL TO .001"WILL WORK ON VIRTUALLY ANY COIL SPRING DESIGNED FOR A RACE CARCOMES WITH AN EASY-TO-USE PRECISION DIAL INDICATOR TO MEASURE SPRING TRAVEL, A DIGITAL READOUT, & REMOVEABLE LOAD PADTHE LOAD PAD LIFTS OUT & CAN BE USED AS A PORTABLE SCALENOTE: 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 INCONSISTENT. COIL SPRINGS CAN VARY AS MUCH AS 5% FROM THE STATED RATE. THIS IS NORMAL MANUFACTURING TOLERANCE