There are quite different types of ferrite beads, e.g. beads on leads, surface mount beads, chip beads, wound beads, with different impedance and frequency range and current rating. You should narrow down the range you are talking about.
Chip beads e.g. mostly have impedance maxima between 100 MHz and several GHz. Low MHz range would be rather expected for wound beads. Ferrite beads are usually inserted to increase the high frequency impedance of a connection wire or a circuit branch. They can be also part of low pass filters.