Mini-Beam SM2A312 Series The SM2A312 series of photoelectric sensors from Turck Banner are self contained 24 to 240V ac operated sensors with SPST solid-state outputs. The Mini-Beam SM2A213 series are compact high performance sensors with 18 mm threaded lens and are available in opposed, opposed clear plastic, polarized, non-polarized retro-reflective, convergent, diffuse and glass or plastic fiber optic sensing modes.