I've had to replace the bulbs. The small ones are 150 W. I don't remember where I bought my 150 W worklight.
150 W replacement lamp:300 W replacement lamp:
The standard halogen worklamp has a 500W bulb
500 W replacement lamp:The dual head worklight has two 500 W lamps.
They take the same cartridge Halogen lamps (that use a spring loaded socket that contacts the ends of the lamp) as outdoor security lights with motion sensors.
I first saw these 150, 300, 500, & 1000W halogen lamps in a TV studio in 1972. Of course they were were the expensive 'color corrected' version & over $45 each. I lost a Cutler Hammer circuit breaker about half the time, when one of the 1000 W bulbs died.