Placons roller track for pipe&joint system. Material: Iron track+ PE roller Length: 4 meters per piece SPECIFICATION: U channel: Aluminium alloy Rollers: Diameter 34mm (Black) Fitting: JY series connectors How to calculate the length of roller track He standard gradient is 6% (~3.5° ), so to measure a track in relation to its overall length, the calculation is follows: The length of the roller track equivalent to the overall length-65mm Margin: The maximum margin must be less than 5mm divided between the two ends. TIPS: 1 Cuting tracks too short weakens the whole level of the rack. Avoid using tracks whose length is different to that of the internal dimension of the level. 2 Protruding tracks may make a risk of injury when assembled incorrectly. 3 The correct way of assembling a roller track must obey blows: The maximum margin between the connector end-stop and the rail is 5 mm. Remember the standard gradient is 6% Track length=overall length-65mm