12v 3-terminal flasher unit for one to four bulbs.  Ref: CLS0183BR

CLS0183BR is a thermal unit (not electronic) and has the terminals marked as X and L; the third terminal is either unmarked or is marked P. The 12 volt supply goes to the X terminal; the wire from the switch goes to the L terminal and the pilot light is connected to the P (or unmarked) terminal.