Instability strips for ﹩{\ell }=0-3﹩ oscillation modes in the upper part of HR diagram. Separate strips are shown for the β Cephei (﹩\omega \;\gt ﹩ 1) and slowly pulsating B-type (SPB; ﹩\omega \;\lt ﹩ 1) classes of pulsating stars. The ZAMS and red edge of the main sequence (REMS) are shown for reference, as are evolutionary tracks for models with selected masses (labeled in solar units along the ZAMS). The red edges of the post-MS SPB strips are drawn with a dotted line, indicating that the positioning of these edges is an artifact of our numerical procedure.