The Cluster mission has emphasized multi-scale processes occurring throughout the Earth’s magnetosphere since 2000. The MMS mission, launched in March, 2015, helps unravel the mysteries of magnetic reconnection with unprecedented time-resolution measurements of particles and fields. Cluster and MMS constitute, for the first time, two tetrahedral configurations that can investigate multi-scale phenomena simultaneously, enabling more precise mapping of kinetic boundaries in a reconnection region and quantitative testing of micro and meso-scale physics. With large spatial separations between the two missions and different orbital inclinations, MMS and Cluster provide us with an opportunity to capture a micro-to-macroscopic picture of plasma processes, which include the structure and extent of reconnection X-lines, reconnection jets and outflow, the generation, structure, and evolution of flux transfer events (FTEs) and dipolarization fronts (DFs), and wave structures, propagation, and evolution. Additionally, in conjunction with the Van Allen Radiation Probes, ARTEMIS, and THEMIS, MMS and Cluster provide measurements of spatial and temporal phenomena in the solar wind, magnetopause, and magnetotail that can affect the radiation belts. Our project will make full use of these unprecedented opportunities to compare, resolve, and understand reconnection process, including FTEs and DFs, etc., as a function of solar activity.