An expression is given for the vapor attraction in high-coercivity constant magnets in the form of rectangular prisms in planar magnetic systems or end magnetic clutches. The expression enables one to correct the attraction of the vapor by the constant magnets as an additional force or load in designing special devices for assembling and disassembling sealed machines and apparatus, in the design of which there are planar magnetic systems or end magnetic clutches, and also for rolling bearings. © 2009 Springer Science+Business Media, Inc.