One TR100VA004 transformer like shown with built in circuit breaker (we also have listed some similar TR100VA002 which is 2 wire 120v only, the difference is the TR100VA004 is 4 wire optional input voltages 120-480 as pictured) Great for industrial, alarms, PLC, CCTV or anywhere you need 24VAC up to 96VA (approx 4 amp) We do not know the history, but they looked to have been installed in metal housings intended for air pressure monitoring or something similar, but looks to have never been put into service as there was no dust or signs of age/use other than handling. Possible used for an emergency event or one time setup? no orig box, no manual may have light sign of handling/installation Pict is sample all are similar and guaranteed good on arrival Product Details Brand FUNCTIONAL DEVICES INC / RIB Manufacturer Part Number TR100VA004 Connection - Primary Wire Lead Connection - Secondary Wire Lead Enclosure Finish No Finish Enclosure Style Open Frequency 50/60 Hz Includes Circuit Breaker Input Voltage 120V AC or 240,277,480 Mounting Dual Hub; Foot NEMA Enclosure Rating Not Rated Operating Temperature - Maximum 140 F Operating Temperature - Minimum -30 F Output Voltage 24V AC Overall Depth 3.97 in Overall Height 3.03 in Overall Width 2.51 in Phase Single Power Rating 96 VA Protective Device Circuit Breaker Standards CE; RoHS; UL Listed Sub-brand RIB Temperature Rise Not Rated Wire Lead Length - Primary 8 in Wire Lead Length - Secondary 8 in