The Sony SRF-42 is a terrible FM radio and not much better as an AM radio. It does one thing very well, though: AM stereo reception.
It may also have been the most widely distributed AM stereo radio. It was distributed in the mid-1990s through Radio Shack stores, among other places. It was sort of a last gasp of AM stereo: fewer and fewer AM stations were broadcasting in stereo. Even so, the industry had finally settled on one standard. In addition, a defined pre-emphasis curve was established for AM radio around 1990; this radio matches that curve to enable more accurate frequency response.
The SRF-42 is also the only Sony AM stereo radio that can tune the extended AM band (1610-1700 kHz). Sony's other AM stereo efforts were from the mid-1980s, when the extended band wasn't in use yet. I bought my SRF-42 in 1995 (I believe) in Kansas City.
Other AM stereo radios from Sony: SRF-A1 | SRF-A100 | SRF-AX15