It will fit in a 4" hole, but just barely.... The trick is that you must hold onto the XLR connector when putting it in the drum, as there's no room for fingers on a 4" hole. For this reason my standard front head has a 5" hole, offset.
Good sounding cheap mic, I keep one in my home kick, either use it or not; or sometimes a B52 or PR40 in the hole, just depends what one's after. Sounds great close miking a floor tom, either above or under.
Wouldn't dream of supplying it for a pro gig for some touring band, just 'cos nobody has heard (of) it, but for local groups playing a bar.... seems to work.
Hope this helps.