This funnel is not a good funnel because it has a curvature to the lower part of the stem that will not allow this funnel to bottom out inside of the jar. It will fit inside of the jar, but because of the curvature, it is necessary to hold it upright or it will tilt.
If you want a funnel that looks almost identical, but that fits properly inside the mouth of a standard-sized canning jar, try this one:
5-Inch Wide Mouth Canning Funnel - Stainless Steel
These funnels look almost identical, except for the fact the Fox Run funnel will not properly rest inside of the standard sized jar, but the funnel in the above link will feel like it is locked inside of the standard sized canning jar. I would classify this as a funnel that was just not properly designed.
If you want a funnel that will fit inside of a wide mouth canning jar, this one fits the bill:
RSVP Endurance Wide Mouth Canning Funnel
A little bit more expensive, but made out of a heavier guage of stainless steel and fits nicely inside of the jar.