The 100-Series door knobs feature cylindrical construction for use on a variety of commercial doors. Classic Ball (B) and Plymouth (P) styles make these excellent retrofit and replacement locks. Compatible with many retrofit cylinders such as LSDA C500, Ilco, GMS and most High-Security brands including Medeco, Assa, Schlage Primus, Kaba Peaks, etc. Latches and cylinders must be ordered separately.