This document provides an overview of REDI (Ruggedized Enhanced Design Implementation), which defines mechanical design standards for plug-in units in VPX systems. It discusses REDI form factors and covers air cooling and conduction cooling designs. For air cooling, it describes design considerations like minimum PCB thickness and cover specifications. For conduction cooling, it outlines the role of frames and covers in transferring heat. Important rules are highlighted, such as covers being electrically grounded and type 1 units requiring both primary and secondary covers.