Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: what is the width between inlet & outlet? Am using in limited space.
Document: Very well made, heavy-duty filter. Provided with four deep, blind screw holeson top for mounting. Appear to be for about #12 or 6MM screws. NO bleed valve on top,a good feature (for me) as these usually tend to leak. Bowl sealed with double O rings.Two caveats however:. [1] Inlet & outlet only 1/2". Not suitable volume of water for a (single)whole house filter.
perfect proportions and will work well for what i have planned...the housing is exactly as described and the price was perfect.
Why go and by a $50 filter system when this is the same thing, just less the filter ($4). This is perfect for filtering water to drink or even pet use! The price is wondeful and the product is great!
When I wrote to them, they called me and said they were looking into the shipping charges to be sure they were reasonable. They wrote me back saying  "We calculated the freight cost to ship from us in Vista, CA 92081 to you and the going rate is $16.76 for UPS Ground. We only charged you $15.96 and we feel this is a fair price."
When I was building my homebrew beer filter system I found these. Bought a couple and ganged em together. I've got no real complaints about them, they work exactly as they are supposed to. They hold a 10&#34; filter and run liquid through it.The bottom portion feels like high quality plastic, fairly thick and heavy, more than enough to survive being used for beer.My only issue is with the construction of the top portion.
Unlike Watts Whole House filter housing,  this filter housing DOES NOT have separate selection of By-Pass, off, Filter selection. So, you must have to install shut off value of some sort before water reaches this filter housing.
Unfortunately, I have very heavy iron requiring multiple filters..[2] I could not find any source of a bowl wrench or (more importantly) anyreplacement bowl O rings. These O rings are not like any O rings on my otherfilters. NOT ordinary "bowl O rings"..Just a guess: The VERY low price and lack of any parts support would indicate tome these are a discontinued item being 'dumped'. I paid $8.74 each, I see they'renow down to $8.00.
This item is fine, but does not include any provision for mounting. I ordered 3 of these filter housings.
The product was as described and worked correctly. Would buy again if the need was there. Be aware you still need to purchase a filter.
So much for the $8.00 filters..5-14 update:I see there is more effort to distance the (cost of) filters from the O rings. They're now up to $19.00. Way over a 100% rise in mark-up. (Assuming theO rings are still $8.00....probably unlikely. Good 'ol captialism at work.) Still no wrenches.
Answer: 4.56 inches edge to edge