It's a horizontal channel frame with a 1" stack of EI-75 laminations. One side of the bobbin has solder lugs protruding. Overall dimensions are:
Mounting centers 2 13/16 inch
Weight 21 ounce (600 grams)
Height 2.00 inch
Width (outer edge of mounting tabs) 3.25 inch
Depth (bobbin plus solder lug) 2.125 inch
The core itself is 1.875 by 2.25 by 1.00 inch. The bobbin width is 1.75 inch and the solder lugs protrude another 0.375 inch on the one side.