DB Jacket: How many buttons on the sleeve?

[Hap Hapablap]

Does a double-breasted jacket need to have 4 buttons on the sleeve/cuff, or can it be 3 or even 2? Any protocol of the former or evidence of the latter?
Thanks!

 

[Edward]

To the best of my knowledge, outside of military uniforms there is no set requirement. None to three is all fine by me. More than that and it can start to look a bit much, especially on a blazer with contrasting buttons.

 

[Gin&Tonics]

I believe in the military the standard is 3. Since the blazer with brass buttons arguably has its origins with the British Navy, 3 would perhaps be the most traditionally correct number.