The fixtures in the MAC III series use the following lamps:
MAC III Profile
MAC III Performance
Use the Osram HTI 1500W/60/P50 Lok-it, P/N 97010347
MAC III AirFX (and Quadray)
MAC III Wash
Use the Osram HTI 1500W/60/P50 7mm Lok-it, P/N 97010348
The only difference between these two lamps is in internal design and optical characteristics. These are optimized for the fixtures that the lamps are approved for.
It is possible to use the MAC III Profile and Performance lamp in a MAC III AirFX or Wash -- and vice versa -- but for best optical performance we recommend using the lamps only in the fixtures they are approved for as listed above.