Sekonic 012069 Transmitter RT-GX for L-858D Light Meter

The Sekonic RT-GX Transmitter Module is a specialized internal wireless module that brings radio flash control to the L-858D-U Speedmaster light meter. By installing this module in the meter's battery compartment, photographers gain the ability to trigger Godox and Flashpoint flashes and remotely adjust their power output without leaving their metering position. This integration eliminates the back-and-forth workflow of metering, walking to the light to adjust power, and metering again — instead, you can take a reading and immediately dial in the correct flash power from the meter itself.

Operating on the 2.4GHz Godox wireless X system, the RT-GX provides stable radio communication for managing multi-light configurations and precise exposure ratios. The module's user-replaceable design means installation is a simple process that doesn't require tools or professional service, and its compact form factor fits neatly alongside the batteries without adding any external bulk to the meter. At just 0.02 pounds and roughly 1.3 x 1.1 x 0.43 inches, the module is remarkably small, reflecting its focused purpose as a radio bridge between your meter and your lights. For photographers invested in the Godox or Flashpoint ecosystem who rely on precise light metering, the RT-GX turns the L-858D into a centralized lighting management tool that streamlines both studio and on-location shoots.