Paint code help, is 'U' relevent in the code?

[xsaravtr]

Code on my C Class is 775, Iridium Silver.

I'm Looking around various places on the web for a touch up paint kit and there are codes of 775 and 775U.

Anyone know what the difference is? Is it a different shade/finish?

Thx!

[anonymous-user]

U usually denotes metallic.