This Teflon block is a wear pad installed in the threshing drive of the parent combine. It provides a low-friction sliding surface between moving components in the drive system, reducing metal-to-metal contact and heat buildup. As the block wears over time, clearance in the drive linkage increases, which can lead to vibration and uneven power transmission. The manufacturer machines this block to the original thickness and hole spacing so it seats correctly without modification. On installation, verify the block sits flat against its mounting surface before securing the fastener.