Pencil gauges can be unreliable because they rely on friction to provide a reading. If you do insist on using one, use one that has a more appropriate range for tractors such as a 0-30 psi gauge.
I recently bought a few of these as they had very good reviews on Project Farm's YouTube channel.
I agree on the pencil gauges being handy, and potentially unreliable.
Due to Wisconsin being hot in summer and well below freezing in winter I learned mechanical gauges are far more reliable than anything that runs on batteries.
Older Milton products have been reliable for me, reviews of new products suggest they're made in the U.S. from imported parts and frequently leak (bad seals, suggesting poor quality control).
Personally I'd get a "value-based product" like
@Old Machinist mentions so if it fails I'm not out a block of treasury bills.
I actually bought a
Jaco analog gauge that doesn't have to be on an air line to work, because if I'm going to get stuck with what's basically a Chinese made product assembled in the US I might just as well buy a quality Chinese product for 50% less. They also make an
inflator with analog gauge which is likely a better option as it's easier to read than the Milton original service station gauge and 1/2 the price, though not nearly as sturdy as the Milton either. Although right now the gauge
@Old Machinist linked to is $13+$6s/h which is a really good deal.