Radiopopper PX system allows you to use the automatic and high-speed sync functions built into your existing flash units without regards to whether or not the master and slave units can see each other. The Radiopopper enables free placements of your lights and controlling the output power of each slave from the camera body manually or automatically via the camera's ETTL or i-TTL system.
The PX Receiver receives signals transmitted by the transmitter. The receiver then uses its own inner light source to duplicate this light signal. The light is discharged through a window on the back of the Receiver unit directly into the infrared sensor on a slave flash, that slave flash responds to the duplicated light signal just as it normally would had it seen the light directly from the master flash.