Hydraulic reservoirs and accessories store unpressurized hydraulic fluid used in hydraulic systems. Hydraulic reservoirs are typically made of corrosion-resistant stainless steel, aluminum, or plastic for continuous storage of hydraulic fluid. Accessories support reservoirs. They include filler indicators, breather filters, breathers, and diffusers. Indicators monitor fluid levels in the reservoir. Breathers and filler breather filters allow filtered air or fluid inside the reservoir and prevent contaminants from entering the connected hydraulic system. Hydraulic flow diffusers slow the flow of fluid returning to the reservoir.