Sideways ROM from KDS Electronics. There are two versions, one with 4-sockets, one with 5-sockets. All versions included a free "utility rom" (unknown what kind of utilities it may have contained).
Old version (7/1985)
4-socket ROM board, accepts 2K, 4K, 8K, 16K chips (ie. both 24pin and 28pin chips). According to the advert, it also supports chips slower than the recommended 200ns - the advert isn't too clear about this, but it sounds as if it can produce memory waitstates, via /WAIT signal or so.
New version (4/1986)
5-socket ROM board, accepts 8K, 16K chips (ie. 28pin chips).
Photos
KDS Sideways 6-socket ROM Box supplied with a free KDS ROM v4.88 - appears to be older version of ROMDOS