The Airborne Research Instrumentation Testing Opportunity (ARISTO) is a NSF-sponsored program that allowed researchers to test novel instrumentation during a 3-week campaign based in Boulder, Colorado at the National Center for Atmospheric Research’s (NCAR) Research Aviation Facility (RAF) aboard the C-130 aircraft. While the HRToF-CIMS instruments have successfully flown on previous campaigns (SENEX and WINTER), for ARISTO we tested a novel “wall-less” inlet. Many of the gases we measure are semi- or involatile, some of which can be lost or undergo chemistry on the inlet surface or exhibit slow response times due to interaction with inlet surface. The “wall-less” inlet is porous PTFE housed inside a vacuum chamber. Molecules that come into contact with the inlet wall are continuously pulled through and pumped to exhaust, such that the air that reaches the instrument has never come into contact with the inlet surface, thereby minimizing loss and artifacts.