The used Olympus FC-WR Wireless Radio Flash Commander lets you control multiple flashes. Key features include:

Remote Flash Commander. You can use the Olympus FC-WR Wireless Radio Flash Commander to remotely control multiple flashes using 2.4 GHz radio transmission. It has a 98.4-foot transmitting range, provides 3 groups for triggering, and can control an unlimited number of flashes with the separately rentable Olympus FR-WR Wireless Radio Flash Receiver.

Easy Setup and Control. This commander boasts a top LCD for reviewing settings, and dedicated buttons that control each of the three groups. It is powered by two AAA batteries (not included).

High-Quality Build. Like Olympus OM-D-series cameras, this receiver is splash-, dust-, and freeze-resistant, so you can use it in inclement conditions.

Compatibility. As of January 2019, the Olympus Wireless Radio System is only supported by the Olympus OM-D E-M1X / E-M1 Mark II / E-M1 / E-M5 Mark II and PEN-F.