I'd love to hear someone answer yes and direct us all to where they can be purchased.
Judging from the way 6" IC cans are designed I'd say an IC can with a 4" diameter would have to be way tall or use a way short lamp.
Fluorescent perhaps?
LITOLIER. (i'll dbl check the mfg.)
Depending on the bulb installed.
The customer bought them, I checked the papers and..... all good.
I just did 8 2 wks ago.