SMB (SubMiniature version B) connectors are coaxial RF connectors developed in the 1960s. SMB connectors are smaller than SMA connectors.
They feature a snap-on coupling and are available in either 50 Ω or 75 Ω impedance. They offer excellent electrical performance from DC to 4 GHz.
An SMB jack has a male center pin, while an SMB plug has a female basket.