The Focal Spot Test Tool is an acrylic cylinder housing a range of bar patterns that can be used at assess focal spot size. The patterns range from 0.84 lp/mmm to 5.66 lp/mm. The visually observed limiting resolution can be simply converted into an effective focal spot size. This process is simpler than the use of an IEC slit camera and can be easier to interpret than a star pattern. This product includes a 5-year warranty.