Boris developed and pioneered transition radiation detectors (TRDs) for particle tracking and particle identification. His experience and expertise with this sophisticated detector dates back to the early 1970s and there is hardly a TRD in the world to which Boris has not significantly contributed. Among them are the TRDs of the HELIOS spectrometer at the Super Proton Synchrotron, the ZEUS and HERA-B experiments at HERA, the AMS spectrometer that will fly in space and the huge Transition Radiation Tracker (TRT) of the ATLAS experiment at the LHC. Most TRDs, whether at accelerator-based experiments or in space, were built following one or other of these examples and profited from the intensive and careful R&D programmes that Boris and his collaborators carried out.