SPECIFICATIONS:

RTCA Document:  DO-138
ARINC characteristic:  570 
MIL specification:  MIL-C-6781
Altitude:  45000 ft max 
Temperature:  -54 to 55C (operation)  Dimensions:  5.75"W x 2.625"H x 2.5"H 
Frequency selection:  BCD binary code switching per ARINC 570
Duty Cycle:  Continuous