Comparison of the P − L relations of δ Scuti stars and Cepheids in the J (upper left), H (upper middle), and K_s (upper right) bands, alongside the comparison of δ Scuti stars and RR Lyrae stars in the W₁ (lower left), W₂ (lower middle), and W₃ (lower right) bands. The period range for δ Scuti stars spans 0.02–0.25 day (Chang et al. 2013), for Cepheids 3–100 days (Persson et al. 2004), and for RR Lyrae stars 0.2–1 day (Lafler & Kinman 1965).