By combining ion mobility mass spectrometry (IM MS) with time-of-flight MS (Tof MS), Waters revolutionized the structural analysis of peptides, proteins, and protein complexes. Waters SYNAPT range of mass spectrometers have generated important breakthroughs in the determination of overall size, shape, and subunit architecture of protein complexes. For post-translational modification studies, the SYNAPT G2-Si also offers a unique implementation of ETD. ETD is performed in the trap-region of the Triwave device allowing for the optional, supplemental activation of ions by CID. All told Waters Omics Discovery Platform allows for extensive characterization of the primary and tertiary structure of proteins.