A subgroup of Beta Cephei stars in which non-radial pulsation is particularly significant. Multiple periods (0.15–2 or more days) are often present, but all tend to be highly unstable. The type star, 53 Persei (also known as V469 Per), has a range of 4.77 to 4.86 mag. and several periods in the range 1.67–3.64 days. They are also known as 53 Persei stars.