Question

line wrench
a line wrench is a special type of wrench designed especially for loosening pipe and cable fittings. resembling a combination between a box - end and open - end wrench. this wrench design grips the nut on more edges, so you can apply more force to either loosen or tighten.
line wrenches are commonly used to loosen/tighten brake, power steering, transmission/engine oil cooler line fittings and cable ends. an open end wrench should not be used to initially loosen these types of connections, because the risk of slipping and damaging the fitting is considerable.
why is the use of a line wrench preferable when loosening a brake line fitting?
the line wrench limits the maximum transferable force.
a line wrench grips the nut more securely, reducing the risk of slipping that causes damage.
a line wrench prevents snapping off a bolt head.

Explanation:

The text states that an open - end wrench has a high risk of slipping and damaging the fitting when used to loosen certain connections like brake line fittings. A line wrench grips the nut on more edges, providing a more secure grip and reducing the risk of slipping and damage.

Answer:

A line wrench grips the nut more securely, reducing the risk of slipping that causes damage.