What kind of radiator is this?

Does anyone know what this type of hot water radiator is called, and if they are still available somewhere? I have a couple in an older home, installed in recessed areas. They measure 13" high, are 9-1/2" deep, and the sections are 10" wide. They put out a lot of heat. I am looking to add a radiator to another area of the home and am constricted in space. I need to find something that will put out at least 5000 BTUH, but will fit in a 17-3/4" high space (due to window opening) and is less than 50" wide (including piping). I thought if I could find one of these somewhere, it would do the trick. Any help is sincerely appreciated. Thanks.