Power is adjustable in 1/10 stop increments, from full to 1/8 power. Its model light intensity may be controlled coupled to, or independent from the strobe power levels you select. This kit provides ample power to light a three-four person full-length portrait.The Impact VS300 is a good choice for building a system - its built-in optical slave fires the flash without wires, from the light of any other flash system. This kit includes air-cushioned light stands that rise to a maximum of 10 feet, 43" white translucent umbrellas, sync cord (Mini plug to PC), and soft padded case with shoulder strap and internal movable dividers. The 43" umbrella is suggested for use in mid-length portraits for one or two persons. The kit bag accommodates two monolights, reflectors, cables, umbrellas and light stands. It has a nylon exterior and padded interior, with zipper closures.Impact Two Monolight Kit with Case (120VAC) Specs Maximum Watt/Seconds: 300 Guide Number: 182 in feet, @ ISO 100 Recycle Time: 2 sec @ full power Flash Variability: Full to 1/8 power in 1/10 stop increments User Replaceable Flashtube: Yes Changeable Reflector: Yes Modeling Light Wattage: 100 Operating Voltage: 110-120VAC, 50/60Hz Built-in Slave Cell: Yes, 10 m range Circuit Protection: Fuse Fan Cooled: No Auto Dump: Yes - limited - strobe fires automatically as power is turned down Dimensions: 11.6 x 8.5 x 6" (29.5 x 21.6 x 15.2 cm) with 6" reflector Weight: 3.5 lbs (1.6 kg) Kit Bag Exterior Dimensions: 34 x 13.5 x 8" (86.4 x 34.3 x 20.3 cm) Interior Dimensions: 32 x 12 x 7" (81.3 x 30.5 x 17.8 cm) Load Capacity: 45 lb (20.4 kg) Weight: 6.25 lb (2.835 kg) This Impact Two Monolight Kit with Case (120VAC) includes: 2 x Impact Digital Monolight 300W/s (120VAC) 2 x Impact White Translucent Umbrella (43") Impact Light Kit Bag (34 x 13.5 x 8") 2 x Impact Air Cushioned Light Stand, Black - 10" (3m)