There is a misprint on the the Nikon USA website. This diffuser does not fit the Nikon SB28 SpeedLight.
A good reason to buy original equipment.
It puts out so much even, balanced light from one source that a totally unlit room appears bright. My main use is for superwide-angle interior photos. On a Nikon SB 800, even with a 10 mm, digital SLR lens, there are no dark edges.