See: Arrowmax

Arrowmax is added the new Diff Checker to their electronic line up. The newly design, built-in battery diff checker is small, compact and powerful. It is designed to evaluate and determine the differential hardness but also it can be used as a diff run-in device with fresh diff. The device features a 5-digit decimal display to provide the most accurate value possible. The Diff Checker can be easily charge using a micro USB connector and it comes with a standard outdrive insert and a 7mm nut driver adapters while an optional adapter set for 1/8 Buggy and GT is available as option.