Neewer 500W Professional Photography Studio Strobe Flash Light Kit - 2 Strobe Flashes, Stands, Umbrellas, Flash Trigger, & Reflectors! 2 x 33" Black/Silver Umbrella provide softening, with a harder shadow than a regular white umbrella. Light loss is usually ~1.5 f/stop compared to the same light used direct, bare light. The black backing cuts down on stray light. Professional Studio Lighting Kit 500W TWO (2) Professional Studio Strobe: 250di, with their own 75-watt modeling light. This strobe is typically used for background, fill, or highlighting. It easily creates a wide-dispersion glow when used with the gel set. A studio kit with two strobes can achieve tremendous results. 250di is equipped with buzz function. The flash can be adjusted from 1/8 to full 250W. The modeling lamp can be adjusted from full to proportion. With pre-flash system, it can fire on the second flash synchronously. Note: ( 2 flash strobes can be triggered by 1 trigger set , you don't need extra receiver for the other light )