Calcutta casting block colors?
 

Anyone know how Shimano color codes them?

I have gray and I have clear.

Which are slower?

Shimano Colors
 

My 400S has grey and clear while my 400TE has green and rose. Both the clear and the rose have smaller diameter barrels which leads me to think that they have smaller tips that rub and slow down the spool. I generally use just 1 or 2 of the smaller ones to get the most distance but if I'm casting into a big headwind I'll add more. The TE is much easier to adjust. It's my go to reel.

2, 400s both have grey and clear

Thanks Paul.

Any clue which are which?

(I've got a 400s from Mac and I just picked up a Calcutta Conquest 400)

I don't know but I set mine one in one out all the way. I alternate every other one. I rarely (but sometimes we all do) have a 'lash. Had one two weeks ago standing on a rock and off balanced. Took my thumb off to catch my balance and WOW!! Had to cut the 'lash out.