Due to variations in pressure or temperature, the volume of air inside the equipment can expand or contract and in the absence of a venting port, the structure could crack and collapse. Breathers are therefore essential for the structural integrity of small enclosures and instruments. However, the small size of some equipment makes the use of conventional breathers impracticable. Brownell has added a “mini” category to its range of breathers, designed with a standard M3 metric thread for fitting that can be screwed in place or mounted using a locking nut.