Compatible with FUJIFILM, Canon, Nikon, Olympus, and Sony cameras, the Lux Junior Retro Camera Flash from Godox is a diminutive 3 x 2.8 x 2" light source with basic features and is small enough to have it regularly mounted on your camera.
Called a "retro" flash, the unit has a simple dial that correlates ISO with apertures, power levels, and shooting distances. For example, if you want to shoot at 5' with an ISO of 400, the dial lines up f/4 and 1/8 power. The flash has an Auto Mode, too, that defaults to f/2.8 at ISO 100.
Control features include an Optical Mode that offers S1 and S2 settings. In S1 the flash will fire in response to another manual or TTL flash, while in S2 the Retro Flash will respond similarly, but ignore the initial flash. The unit runs on separately purchased AAA batteries and comes with a triggering cable and a storage bag.