B-55-04-04 - 1/4" x 1/4"
B-55-05-05 - 5/16" x 5/16"
B-55-06-04 - 3/8" x 1/4"
B-55-06-06 - 3/8" x 3/8"
B-55-08-06 - 1/2" x 3/8"
B-55-08-08 - 1/2" x 1/2"
B-55-10-10 - 5/8" x 5/8" 
B-55-12-12 - 3/4"  x 3/4"
B-55-14-14 - 7/8" x 7/8"

This brass hydraulic SAE 45° fitting is equivalent to the following:
-SAE 010201
-Eaton Weatherhead 55