Circuitron
PS-3 Power Supply

Walthers Part # 800-5304, p. 773 Walthers 2012 HO Scale Reference
A scale, $16.95, not currently in stock at Walthers, Expected: Unknown

 
Designed to power the EF-1 Emergency Flasher in situations where battery operation is undesirable. Accepts AC or DC input of 10-18V and converts it to 9V DC.