Control/Dimming What would you use this transformer for?

[Oldschool]

I am hoping to figure out what one would use the following for:

10 inch square metal box with a C-clamp on top - Stage pin marked 110v in and stage pin marked 28 volt out - Box contains large / heavy step down transformer.

What goes on a grid that uses 28 volts? As always, Thanks for your help.

 

[soundlight]

A single ACL fixture.

 

[derekleffew]

A single ACL fixture.

Winner winner chicken dinner.

GE - 4552 This lamp is a 250 watt, 28 volt PAR64 sealed beam. It is a PAR64 with a 7X8 beam spread, screw terminals and an overall length of 3.7 inches. It is rated at 25 life hours.

GE - 4559 This lamp is a 600 watt, 28 volt PAR64 sealed beam. It is a PAR64 with a 11X12 beam spread, screw terminals and an overall length of 3.7 inches. It is rated at 25 life hours.

 

[Oldschool]

Thanks to derekleffew and Soundlight for taking the time to educate.