This prevents the string from snagging or tangling around the center ball. Sharp square corners may be uncomfortable and cause snagging on socks. An obstruction can be any type of rough surface capable of snagging debris. The helmet of the "secutor" was smooth and round to avoid snagging the net. The disadvantage of a buddy line is an increased risk of snagging and entanglement. There is a risk of objects snagging in the vents. This can also increase the risk of snagging in an enclosed environment. It was used for CSAR, covert combat operations, and "snagging" reentry capsules from photo-reconnaissance satellites.