Generating realistic network traffic that reflects different network conditions and topologies is crucial for performing valid experiments in network testbeds. There are existing software network emulators that receive real packets, pass them through a simulated network, and transmit them again based on the time they would leave the simulated network. Unfortunately, scheduling packet transmissions in software leads to unavoidable inaccuracies, and the observed transmission times are not correct on very small time scales. We have developed the Percise Traffic Generator to solve this problem by transmitting packets exactly when requested using a NetFPGA card. For scenarios that are very sensitive to packet arrival times, such as Sizing Buffers in Internet Routers, this tool allows researchers to perform convincing experiments exploring a wide range of traffic properties.