RASCO/Reliable® Model A AMDA23 Automatic Air Pressure Maintenance Device , 23psi, 6304001123 F3Res They come with pre drilled

They come with pre drilled holes for easy installation

plug-in and non plug-in with one another and with other switch brands

Escutcheon for use with Viking institutional fire sprinkler model numbers:

Outside Diameter -  3 1/4"

S271BFS420 Fire Sprinkler Head

RASCO/Reliable® Model A AMDA23 Automatic Air Pressure Maintenance Device , 23psi, 6304001123 F3Res They come with pre drilledThe Model A Pressure Maintenance Device (PMD) is designed for use where a source of compressed air (plant air system, tank mounted compressor with a pressure control, etc.) or nitrogen cylinder (equipped with a high pressure regulating device) is available. The regulator in the Model A PMD reduces higher pressure air or nitrogen to a level required by a dry pipe valve, dry pilot line, or a deluge valve based preaction system. The Model A PMD will