This is a Tekno RC Hardened Steel 5.5mm/7.0mm Wrench. The Tekno RC tool product line is expanding. This dual ended tool is perfect for any application requiring a 5.5mm (M3 nut) or 7mm (M4 nut) wrench. It is compact and extremely durable so it fits in the tightest spaces and can be used to really crank on those nuts! There simply is no better wrench on the market for these applications.