This is a tool used to tighten nuts and lock nuts on Mini 4WD cars. ⚫︎It's thinner than standard wrenches, making it convenient for use in tight spaces and for attaching small parts. It can also be used to install and remove long screws! ⚫︎One side is approximately 4mm, and the other side is approximately 4.5mm! The design is easy to distinguish thanks to the markings.