Basically a bracket gets bolted to the spindle, while not permanent it never needs to be removed because the caliper bolts come in through the top. Rotors and calipers come off in minutes. Most likely racing is where they came from.Explain 'radial mount'
I don't feel like googlefu-ing right now.
Once you have brakes that work in this manner, it's hard to think about buying anything else.
The alcon brakes on my saleen explorer were radial and i loved it.
Not all setups are that expensive. There are ways to acquire the calipers cheap since many are 130mm spacing.