Analog Filter 1 (AF1)
The Analog Filter 1 (AF1) is used to filter the DC signal leaving the power pack. This filter pack corrects flickering in lighting effects and low-speed auto-reversing. Only one AF1 is required to smooth out the operation of all of the locomotives being controlled by one DC power pack.
 
Dimensions: 1.84" x 1.01" x .68" or 46.83mm x 25.68mm x 17.26mm
 
MSRP $28.95  SKU: 1483
https://www.tcsdcc.com/product-page/analog-filter-1-af1