Flow conditioning is one of the most critical aspects dealing with any type of volumetric flow metering. Flow conditioning is the final buffer between the flow meter and the upstream piping layout and is responsible for eliminating swirl, restoring flow symmetry and generating a repeatable, fully developed velocity flow profile. Even though modern advancements have resulted in low uncertainty, high repeatability devices that are effective across a range of flow rates, proper utilization of flow conditioner is still required to maximize the meters’ performance, diagnostics and ensure the most stable long term flow measurement. All flow conditioner technologies are not made equal, as commonly used designs such as AGA tube bundles and straightening vanes can actually cause more measurement problems than they resolve. This paper will focus on two main types of flow conditioners; perforated plate systems and tube bundles.