FlashZebra, an American flash accessories company, have released a pair of sync adapters allowing RadioPopper JrX flash triggers to remotely control the power on Nikon speedlights. This will come as an embarrassment to RadioPopper, who have yet to release their own “RPCube” designed for the same purpose.
FlashZebra offer two models – a hotshoe adapter (pictured)Â and a 3-pin sync adapter.
You can also learn how to make your own Nikon RPCube in this Flickr thread. Canon RPCubes are a bit trickier, but still possible. Read more here.