What we appreciate most about the Lucy EA is its versatility. It facilitates quality assurance of the entire SRS process including output measurements using a small ion chamber, off-axis Winston-Lutz using the 5 BB targets, as well as multiple film inserts allowing for validation of planar dose distributions of a single isocenter multi-target treatment. A single phantom, which is both easy to setup and change configurations, is invaluable to a busy clinical physicist.