This is the Spark Recording kit for the 2.5m long Air Track. It consists of a pair of special insulated tracks that carry the spark electrodes and a pair of insulated tracks that carry the paper tapes. All parts are in the kit except the Spark Generator. The pens that fit to the gliders carry the spark from the electrodes to the paper tape without anything touching to spoil the friction free operation. The sparks going through the paper tape make black dots which are measured in pitch to calculate velocities and accelerations. The Spark Generator to create the sparks is 0118-001 and is not supplied with the kit.