Although the hydraulic fluid moves through a relatively closed system, hydraulic filters are extremely important. The nature of most hydraulic machinery entails the regular creation of damaging metal chips and filings, and the hydraulic filter is responsible for removing these objects. Other internal contaminants include plastic and rubber particles generated by abraded seals and bearings. Hydraulic filters will also remove external contaminants, such as dust and dirt that make their way into the hydraulic circuit. These functions are integral to the consistent operation and longevity of any hydraulic-powered device, and unfiltered hydraulic fluid will lead to increased leakage and system inefficiency.