Honeywell 1/2″ direct ignition dual automatic combination valve

Honeywell 1/2″ direct ignition dual automatic combination valve, 24vac, single stage, step opening, 3.5″wc full rate; 1.2″wc step regulator setting, 20-200 cfh capacity, 1/2# pressure rating, 1/8″ pressure tapping with plug, for use with hot surface and direct spark systems