Flashes and monolights from Profoto are extremely popular with professional photographers that want consistency. They’re not cheap, but they last, are well built and overall pretty incredible. There surely are more affordable options but none that also have the color consistency that Profoto offers. The B1s are some of their most popular lights.
Profoto has provided support for the Canon and Nikon camera systems for a while now; and today they announced that their collaborating with Sony. In early 2017, the Profoto Air Remote TTL-S will be available to support the various cameras in the Sony a7 lineup. The remote offers full TTL and HSS capability with Profoto’s Pro-10, D2, B1, and B2 flashes.