What is a common feature of Class 4 lasers?

Class 4 lasers are recognized for their significant potential hazards, which include risks of fire and eye injury. These lasers emit high-power beams capable of causing severe retinal damage on direct exposure, and even reflective surfaces can scatter the beam, leading to unintended injuries. Additionally, their ability to ignite flammable materials places them at a greater risk for fire hazards compared to lower-class lasers. This characteristic necessitates stringent safety protocols to protect individuals in the vicinity, highlighting the importance of understanding and implementing appropriate safety measures when working with such powerful devices.

The other options do not accurately reflect the defining characteristics of Class 4 lasers. While they are indeed used in medical settings, this is not their most distinguishing feature when classified compared to the inherent dangers they pose.