This is the Body Reamer from HPI.
Features: Designed to create and enlarge holes in lexan, ABS, balsa polycarbonate-almost any hobby material Extra sharp point starts holes quickly and precisely; razor sharp flutes remove debris while cutting for clean, perfect results Handle is made of knurled anodized aluminum for a secure, comfortable grip A plastic case is included for safe storage Purple anodized handle.
...more about the Hobby Products Intl. U Body Reamer