I'm glad you said it before I had too. Absolutely no disrespect to
@size26s as he is lean and hard. Due to that conditioning he looks bigger than he is. Add a pump, good lighting, tanning and the perfect pose by himself (bicep pulled in hard against the lat) and that's the bodybuilding illusion of looking bigger while than you are.
A lean 20" inch arm is a big arm especially if you're talking no pump but flexed. Let's put this into perspective
@rutman posted a pic a few pages back and I'm sure he's probably rocking 20+ish cold arms and you see how big he is. While he's still lean he's not shredded so you've got to be rocking 21+ inch guns off season to see a 20" ripped arm.