Growtac GT-Roller Flex Bull Cut This valuable item is no longer sold, so there will be no discount. The Flex Bull Cut is a high-performance vibration-damping pad developed exclusively for GT-Roller Flex 2 and 3. Simply placing it under the GT-Roller Flex 2 or 3 turns it into an indoor trainer with the world's lowest vibration levels. It has succeeded in removing an average of 35% of vibrations at speeds of 25-50 km/h. It can also be used with the GT-Roller F3.2.