Yes, the wide flat edges do give you a smaller diameter reflector surface. However, the shape does produce a tighter center spot than any of the "normal size" reflectors I have tried. In my experience, it's much better than the stock reflector, somewhat better than the modified Carley 1940 reflectors, and not quite as good as FiveMegas 2" deep reflector. The bulb hole is the smallest of any reflectors I have used. It is big enough for all of the typical small bipin bulbs (1185, 1111, 1160, etc.) but not big enough for both the ROP bulbs. IIRC, the ROP Low bulb barely fits and the ROP High bulb is just a hair too large to fit. The hole in the Carley 1940 style reflectors is larger and fits both ROP bulbs. The FM Deep reflector hole also fits both ROP bulbs. Personally, I try to use the M2 reflectors when I can and have even drilled one out slightly so I could use it with my ROP. The M2 hole is much smaller than the stock reflector, which i think is somewhere around 1/2 inch.
