The Mark 7 Transformer Breather is designed to ensure equipment that operates under high mechanical strength is protected. Manufactured from weld mild steel, this makes the Mark 7 able to withstand vibrations, shock parameters, and bumps found in electric tractions such as trains and other similar vehicles. A cost-effective way to control moisture, the breather is fitted with oil-seals bowls as well as Envirogel, otherwise known as Orange-Indicating Silica Gel. Envirogel is used in replacement of the typical granular material to give the Mark 7 a much higher dust attrition resistance. The Mark 7 Transformer Breather only needs periodic inspection of oil level and replacement of Envirogel when saturated, which involves low effort. Saturation of the Envirogel is indicated through the colour change from orange to green. The Mark 7 comes in three different models, with varying body lengths to suit different application needs.