Remarkably, ACaPI is the softest DBD-based ion source, barely more energetic than ESI (117% in the softest settings). ACaPI is already on-axis, and the internal energy distribution does not change according to the shape of the waveforms ). To maximize softness, it is important that ions in the ACaPI source pass through the center of the ring , "like a lion in the ring of fire" . If ions pass through the halo of the plasma rather than in the center, or if the voltage is increased, the internal energy in ACaPI increases up to ~170% of that in ESI. Some readers might be interested in the SICRIT device. The brand name itself suggests SICRIT imparts little internal energy. SICRIT is a variant of ACaPI. Unfortunately, the publication reporting internal energy distributions in SICRIT did not include a direct comparison with electrospray on the same mass spectrometer. We thus made the gross approximation that the MS tuning approach in the SICRIT study would be similar to those in the SESI study , also by the Zenobi group on benzylammonium ions, despite that different mass spectrometers were used. With this caveat in mind, SICRIT was found to impart internal energies only slightly higher than ESI (120 to 130% with dry gases, and similar to the ESI study when adding humidity to the N2 gas stream). These estimations agree with the ACaPI results and confirm that SICRIT is nearly as soft as ESI. Further studies with both sources on the same interface, and interface tuning to the softest possible transfer conditions, would be required for better quantitative comparisons.