Where to get quality 20MM button compass?

[Pilot1]

I'd like to get a few compasses to install in my RAT Firesteels. I've looked online and have seen 20MM compasses from $.99 - $14.95 for the Sun, dry compass. Which are best and where to buy a few? Thanks.

 

[R.A.T.]

Sun also makes liquid filled and different grades of the 20mm. Just do an internet search. Personally, I like the dry compass because it seems to be faster and not as apt to hang up.