The 6a is just like the 5, and uses the same coils as the rest of the CZ's. But there isn't a speaker, and hence better weather resistance and splashproofness ( is that a word ?!).
You can't hunt without headphones, so that may be a drawback for some. But since I mainly hunt salt water beaches, I use headphones and want the extra protection of how the 6a is built. I am still using my original 6a bought in 1993. It has 1000's, of hours of use in the salt water enviroment and keeps on going. Never even had it sent in for any type of repair or tune up.
It has been swamped by ocean waves, in torrential downpours and even dropped on a cement floor from 3-4 feet in the air ( accidentially or course) and has never failed.
They are hardly ever for sale, so if you do come across a nice one, get it !!!!!!!