The flash unit is the size of ideal for RX100M2 and also ensure better performance than the built-in flash. Only I have the problem that the flash too dark to black images produced in all camera modes though he flashes fully. With the built-in flash everything is working fine. I suspect that the compact flash is triggered too soon. To go to the problem on the ground I flashed alternately with two flashes against a mirror, the light from the built-in flash could be seen in the pictures, the light of Aufsteckblitzes not although he caused. Now I do not know if a defect on the flash unit or my RX100M2 present I own since about 5 weeks. A search on the internet also did nothing. Bin frustrated because RX100M2 and the HVL-F20M were an ideal team