On the older units (pre Feb 2020) the outer pins are +ve supply and the inner pins -ve. These work from a receiver and pass the receiver supply (normally 5 volts) through to the LEDs connected to the pins.
On the new units (post feb 2020) the outer pins are -ve supply and the inner pins +ve. These work from a receiver and pass the receiver supply (normally 5 volts) through to the LEDs connected to the pins.
The unit has four different flash modes and off.
NB: You must use resistors to limit the current to the LED's
