Rancilio Lever Group Head Screen This 57 mm group head screen fits the Z-9/Z-11 lever group as well as the Z-9/Z-11/AT/AT S group. An older, larger (~63 mm) version existed for the original AT model, so measure before ordering if you own an AT. SPECIFICATIONS 57 mm diameter (current version); older AT version ~63 mm COMPATIBILITY Fits: Rancilio Z-9, Z-11 lever group and Z-9/Z-11/AT/AT S group INSTALLATION Simple DIY swap, the screen lifts out and reseats with light hand pressure or a small pick. PRO TIPS If you have an older AT model, measure your existing screen before ordering, the original AT used a larger ~63 mm screen that this 57 mm version won't replace.