This smart wrench, called a "Flare nut wrench", is used when you need to tighten and loosen screws on hydraulic disc brakes.

It is double-sided and thus has an opening of 7mm and one of 8mm.

Since this wrench has a good engagement with the nut, there is minimal risk of damaging it, and you can also adjust it in very small amounts.

Further inside the wrench. there are 1/4" holes that can be used with 1/4" torque wrenches so you can tighten with the correct torque.